Colorado's spicy ancient history of chili peppers

Botanists and paleontologists, led by researchers from the University of Colorado Boulder, have identified a fossil chili pepper that may rewrite the geography and evolutionary timeline of the tomato plant family.

The team's findings, published last month in the journal New Phytologist, show that the chili pepper tribe (Capsiceae) within the tomato, or nightshade (Solanaceae), family is much older and was much more widespread than previously thought. Scientists previously believed that chili peppers evolved in South America at most 15 million years ago, but the new research pushes that date to at least 50 million years ago -- and suggests that chili peppers were in fact present in North America at that time.

Rocío Deanna, a postdoctoral researcher in ecology and evolutionary biology, and Abel Campos, an undergraduate double majoring in evolutionary biology and molecular, cellular and developmental biology, weren't planning to rewrite history when they met up one afternoon at the CU Boulder Museum of Natural History in 2021. Yet among a group of specimens in its collections gathered from the Green River Formation -- geological treasure trove in northwestern Colorado and southwestern Wyoming -- Deanna spotted a specific, solanaceous trait embedded in one fossil: little spikes on the end of a fruiting stem.

"At first, I thought 'No way! This can't be true,'" said Rocío Deanna, lead author of the study. "But it was so characteristic of the chili pepper."

After they discovered two of these fossils in the CU Boulder collections, Deanna and Campos, a co-author of the study, found one more from the chili pepper tribe in collections at the Denver Museum of Nature and Science. All three fossils are from the Green River Formation in Colorado: the CU specimens from Garfield County and the DMNS fossil from Rio Blanco County.

These chili pepper fossils from the Eocene geological epoch (34 to 56 million years ago) match the timeline of another nightshade fossil found in the Esmeraldas Formation in Colombia, revealing that the family was already distributed across all of the Americas by as early as 50 million years ago.

"The family is way older than we thought," said Deanna, also a faculty member at the National University of Cordoba.

A fruit-fossil history

The nightshade family comprises 3,000 species and almost 100 different genera, including chili peppers. The ancient chili pepper was technically a fruit -- and a berry, at that. While tomatoes and peppers are commonly associated with vegetables, they have seeds on the inside, which officially categorizes them as fruits.

The researchers cannot be sure of the chili's exact shape or color, but it was probably on the smaller end compared to modern day chili peppers. And like its relatives, it could have been quite spicy, according to Deanna.

Deanna and Campos identified the fossil by the unique shape of its calyx teeth: spikes on the end of the fruiting stem that hold on to the pepper, like those which hold a gemstone in a ring.

"The world has maybe 300,000 plant species. The only plants with that kind of calyx is this group of 80 or 90 species," said Stacey Smith, senior author of the paper and associate professor of evolutionary biology at CU Boulder.

Paleontologists collected the CU Boulder fossil from the Green River Formation in the 1990s. But its exact identity remained a mystery for years, in part because there are only a handful of "solanologists," botanists who study the nightshade family, in the world. When Deanna found these Colorado-based fossils, she had just returned from a global search for tomato family fossil specimens, only to find some "just ripe for the picking" right on campus.

"A lot of discoveries happen decades after the specimens have been collected," said Smith. "Who knows how many other new fossil species are sitting in any of these museums? They're just waiting for the right eyes to look at them."

Trickle-down evolution

These chili pepper fossils were around during the Eocene, a geologic epoch that lasted from about 34 to 56 million years ago as the continents drifted toward their present positions. During this balmy time in Earth's history, carbon dioxide levels ranged between 700 and 900 parts per million (twice as high as they are today), and palm trees grew as far north as Alaska. Because little to no ice was present on Earth, sea level was as much as 500 feet higher than it is today.

Scientists had assumed that the origins of chili peppers began in South America roughly 10 to 15 million years ago, where they then dispersed over land and water to the other continents. While Colorado today is home to very few native nightshades and no chili peppers, this new discovery hints that a plethora of plants from the tomato plant family may have existed in North America 40 to 50 million years ago, which have since largely disappeared.

But how did these peppers first get to North America? It's now a case of "the chicken or the chili pepper?"

Experts have theorized that fruit-eating birds, which existed as early as 60 million years ago, may have carried seeds and plants around the world with them in their guts, stuck to their feathers or in the mud on their feet. But these birds also had to be eating something to fuel their journeys -- and fleshy berries, or peppers, make the perfect fuel. Birds may have distributed peppers from continent to continent, but peppers may also have been crucial to the success of those same birds.

So the nightshade family could have easily started in North America instead of South America, then dispersed in the other direction -- and with this discovery, scientists can no longer say for sure, said Smith.

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Botany: From the soil to the sky

Every day, about one quadrillion gallons of water are silently pumped from the ground to the treetops. Earth's plant life accomplishes this staggering feat using only sunlight. It takes energy to lift all this liquid, but just how much was an open question until this year.

Researchers at UC Santa Barbara have calculated the tremendous amount of power used by plants to move water through their xylem from the soil to their leaves. They found that, on average, it was an additional 14% of the energy the plants harvested through photosynthesis. On a global scale, this is comparable to the production of all of humanity's hydropower. Their study, published in the Journal of Geophysical Research: Biogeosciences, is the first to estimate how much energy goes into lifting water up to plant canopies, both for individual plants and worldwide.

"It takes power to move water up through the xylem of the tree. It takes energy. We're quantifying how much energy that is," said first author Gregory Quetin, a postdoctoral researcher in the Department of Geography. This energy is in addition to what a plant produces via photosynthesis. "It's energy that's being harvested passively from the environment, just through the tree's structure."

Photosynthesis requires carbon dioxide, light and water. CO2 is widely available in the air, but the other two ingredients pose a challenge: Light comes from above, and water from below. So, plants need to bring the water up (sometimes a considerable distance) to where the light is.

More complex plants accomplish this with a vascular system, in which tubes called xylem bring water from the roots to the leaves, while other tubes called phloem move sugar produced in the leaves down to the rest of the plant. "Vascular plants evolving xylem is a huge deal that allowed for trees to exist," Quetin said.

Many animals also have a vascular system. We evolved a closed circulatory system with a heart that pumps blood through arteries, capillaries and veins to deliver oxygen and nutrients around our bodies. "This is a function that many organisms pay a lot for," said co-author Anna Trugman, an assistant professor in the Department of Geography. "We pay for it because we have to keep our hearts beating, and that's probably a lot of our metabolic energy."

Plants could have evolved hearts, too. But they didn't. And it saves them a lot of metabolic energy.

In contrast to animals, plant circulatory systems are open and powered passively. Sunlight evaporates water, which escapes from pores in the leaves. This creates a negative pressure that pulls up the water beneath it. Scientists call this process "transpiration."

In essence, transpiration is merely another way that plants harvest energy from sunlight. It's just that, unlike in photosynthesis, this energy doesn't need to be processed before it can be put to use.

Scientists understand this process fairly well, but no one had ever estimated how much energy it consumes. "I've only seen it mentioned specifically as energy in one paper," co-author Leander Anderegg said, "and it was to say that 'this is a really large number. If plants had to pay for it with their metabolism, they wouldn't work.'"

This particular study grew out of basic curiosity. "When Greg [Quetin]and I were both graduate students, we were reading a lot about plant transpiration," recalled Anderegg, now an assistant professor in the Department of Ecology, Evolution, and Marine Biology. "At some point Greg asked, 'How much work do plants do just lifting water against gravity?'

"I said, 'I have no idea. I wonder if anyone knows?' And Greg said, 'surely we can calculate that.'"

About a decade later, they circled back and did just that. The team combined a global database of plant conductance with mathematical models of sap ascent to estimate how much power the world's plant life devotes to pumping water. They found that the Earth's forests consume around 9.4 petawatt-hours per year. That's on par with global hydropower production, they quickly point out.

This is about 14.2% of the energy that plants take in through photosynthesis. So it's a significant chunk of energy that plants benefit from but don't have to actively process. This free energy passes to the animals and fungi that consume plants, and the animals that consume them, and so on.

Surprisingly, the researchers discovered that fighting gravity accounts for only a tiny fraction of this total. Most of the energy goes into simply overcoming the resistance of a plant's own stem.

These findings may not have many immediate applications, but they help us better understand life on Earth. "The fact that there's a global energy stream of this magnitude that we didn't have quantified, is mildly jarring," Quetin said. "It does seem like a concept that slipped through the cracks."

The energies involved in transpiration seem to fall in between the scales that different scientists examine. It's too big for plant physiologists to consider and too small for scientists who study Earth systems to bother with, so it was forgotten. And it's only within the past decade that scientists have collected enough data on water use and xylem resistance to begin addressing the energy of transpiration at global scales, the authors explained.

Within that time, scientists have been able to refine the significance of transpiration in Earth systems using new observations and models. It affects temperatures, air currents and rainfall, and helps shape a region's ecology and biodiversity. Sap ascent power is a small component of transpiration overall, but the authors suspect it may turn out to be noteworthy given the significant energy involved.

It's still early days, and the team admits there's a lot of work to do in tightening their estimates. Plants vary widely in how conductive their stems are to water flow. Compare a hardy desert juniper with a riverside cottonwood, for instance. "A juniper tree that is very drought adapted has a very high resistance," Anderegg said, "while cottonwoods just live to pump water."

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Plants as cold specialists from the ice age

As cold relics in an increasingly warming world, plants of the spoonweed group time and again quickly adapted to a changing climate during the Ice Ages of the last two million years. An international team of evolutionary biologists and botanists led by Prof. Dr Marcus Koch of Heidelberg University used genomic analyses to study what factors favour adaptation to extreme climatic conditions. The evolutionary history of the Brassicaceae family provides insights into how plants may be able to cope with climate change in the future.

"With the challenges of increasing global warming, developing a basic understanding of how plants adapted to severe environmental change is increasingly urgent," stresses Prof. Koch, whose "Biodiversity and Plant Systematics" working group conducts research at the Centre for Organismal Studies (COS). In many cases, their evolutionary past also strongly determines the future adaptability of plants as well as their ability to develop into new forms and types, he continues. The spoonweed genus, or Latin Cochlearia, from the Brassicaceae family separated from its Mediterranean relatives more than ten million years ago. While their direct descendants specialised in response to drought stress, the spoonweeds conquered the cold and arctic habitats at the beginning of the Ice Age 2.5 million years ago.

In controlled lab experiments, the researchers studied cultivated species from both groups to determine how they repeatedly adapted during the relatively rapidly alternating cold and warm periods over the last two million years. A "cold training" indicates that the physiological adaptations to drought and salt stress during their early evolution later helped the plants develop a high tolerance to cold. Although the researchers expected that both groups would show a pronounced response to this "cold training," there appeared to be no significant difference in response to cold stress between the cold specialists of the Arctic and Alpine regions and the dry specialists or species adapted to salt water from the Mediterranean.

Furthermore, the newly emerged plants adapted to cold developed separate gene pools that frequently came into contact with one another in the cold regions. Because spoonweeds have hardly any genetic barriers to contact between species, populations with multiple sets of chromosomes developed that, subsequently, were continually reduced in their size. "Time after time, these species were then able to occupy cold ecological niches," explains Marcus Koch.

While the gene pool of the cold specialists from the Arctic expanded, the European spoonweed population has shrunk since the last Ice Age. Cold habitats in Europe are disappearing in the face of significant global warming, thus seriously endangering all spoonweed species. Only the Danish spoonweed, with its abundant sets of chromosomes, remains unscathed and in some cases is even spreading. "It is the only species of spoonweed that changed its life cycle and flourishes in salt and sand locations. In some of its ecological features, it resembles its faraway Mediterranean cousins," adds Prof. Koch. For the researchers, the physiological adaptability of the spoonweeds makes them a promising model system to simultaneously study adaptations to drought, cold, and salt stress.

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Tree species richness in Amazonian wetlands is three times greater than expected

Compilation of data from forest inventories and botanical collections generates a list of 3,615 tree species in wetland areas of the Amazon Basin. The account makes up for 53 percent of all tree species thus far confirmed for the entire Amazon region.

Throughout the alluvial plains of Amazonia, there are immense forests that are flooded for almost half the year. These Amazonian wetlands encompass a wide array of types of vegetation in or near stream gullies, including blackwater (igapó) and whitewater (várzea) inundation forest, swamp (pântano), white sand savanna (campina), and mangrove (mangue) types.

According to a new study, the region's wetlands are inhabited by 3,615 tree species -- three times more than previously estimated, making these the world's most diverse wetland forests in terms of tree species richness.

The study was supported by the São Paulo Research Foundation -- FAPESP and performed under the aegis of FAPESP's Research Program on Biodiversity Characterization, Conservation, Restoration and Sustainable Use (BIOTA-FAPESP). The results published in the journal PLOS ONE include the most comprehensive list of wetland tree species produced to date.

The authors compiled data available from tree inventories and botanical collections covering the nine countries spanned by the Amazon Basin.

"The list with the names of all the species is the main contribution made by this survey, which is open access. It will serve as a basis for future studies to fill the gap in botanical knowledge of the region's wetlands, especially on tributaries of the Solimões and Amazon rivers. If there were more inventories, the number of species could quickly triple again," said Bruno Garcia Luize, first author of the article and a doctoral researcher at São Paulo State University's Bioscience Institute (IB-UNESP) in Rio Claro, Brazil, who has a scholarship from FAPESP.

The number of species is threefold the number inventoried by previous researchers because the area covered by this study was larger, and more habitats were included.

"Prior studies focused only on whitewater inundation forests and floodplains. We included data for blackwater inundation forests, white sand savannas and mangroves, for example. Additionally, there is a very strong bias toward the Solimões-Amazon river system. We were able to add data for important effluents extracted from rare inventories of forests along the Purus, Juruá and Madeira, among others," Luize said.

For the researchers, the large number of tree species shows the importance of the role played by wetlands in creating and maintaining biodiversity in Amazonia. "This role has traditionally been assigned to the Andes, given the climate gradient there, but the fact that we found almost all families and genera to be well distributed, with species capable of colonizing wetland areas, suggests this ecosystem has been involved in the diversification process for a long time," said Thiago Sanna Freire Silva, a professor in São Paulo State University's Geography Department and coprincipal investigator of the project.

The hard lives of trees

The climate in Amazonia's wetland forests is distinctly seasonal, with fluctuations between dry periods and heavy rain leading to floods, during which the trees may be under water by as much as 8 meters. Wetland habitats can therefore be considered environmental filters that select individuals and species capable of tolerating recurrent flooding and drought during their lifespan.

"It's an incredibly beautiful environment," Luize said. "Blackwater inundation forests, for example, are among the most emblematic images of Amazonia. Tree embryos are submerged for four or five months while they develop. Moreover, monkeys swing through the tree crowns, and the pink river dolphin [Inia geoffrensis] feeds on fish deep in the forest."

Despite the difficult hydrological regimen, the Amazonian wetland tree species currently inventoried account for 53% of all the 6,727 tree species thus far confirmed for the entire Amazon region, according to the latest study.

For the researchers at São Paulo State University (UNESP), the high proportion of trees in wetlands corresponding to 30% of Amazonia's 7 million square kilometers is due to interchange between wetland and upland forest habitats.

Submerged tree roots can rot, and underwater respiration is difficult. "Flooded areas require a different tree metabolism," Luize said. "Some upland or terra firme species are able to tolerate inundation conditions, but studies have shown that populations in the different environments don't manage the same performance. Basically, this means that if you plant a seed from an upland species in a flooded area, it probably won't thrive and vice versa."

This difference suggests either that physiological adjustment occurs during the life of a tree or that the populations found in wetland areas have adapted to that environment. "As a result, we reach an extreme in which species are exclusive to wetland areas or only occur in upland areas," added the FAPESP scholarship holder.

Variations in variations

The duration of flooding in wetland areas varies considerably from one year to the next. "When floods last less and are less intense, the composition of the tree species pool resembles that found in upland areas. However, once these species have developed flood tolerance, even if it is initially a low level of tolerance, the flood provides an opportunity for them to colonize new waterlogged areas. This can lead to specialization in wetlands by some individuals, which become different from upland individuals," Freire Silva said.

Trees may become increasingly flood tolerant or evolve new forms of seed dispersal via water or fish. "Species diversity grows over thousands of years, increasing the variety of niches available," he noted.

South America is considered the region with the largest area of wetlands, a vital ecosystem for the planet's freshwater balance. The researchers stressed the importance of a better understanding of the variations in metabolic and physiological characteristics of both wetland and upland tree species.

"This is a point we need to investigate in more depth, but there are studies that show the effects of dry and wet seasons on forest productivity and on the carbon source-sink balance -- the uptake and release of carbon from or into the atmosphere," Luize said. "Tolerance of hydrological extremes, from drought to flood and back again, is a characteristic of floodable trees. It's important to understand these swings and exchanges on the scale of the basin as a whole."

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99-million-year-old beetle trapped in amber served as pollinator to evergreen cycads

This image shows a dorsal view of the mid-Cretaceous beetle Cretoparacucujus cycadophilus, including the mandibular cavities it likely used for pollination.

Flowering plants are well known for their special relationship to the insects and other animals that serve as their pollinators. But, before the rise of angiosperms, another group of unusual evergreen gymnosperms, known as cycads, may have been the first insect-pollinated plants. Now, researchers reporting in the journal Current Biology on August 16 have uncovered the earliest definitive fossil evidence of that intimate relationship between cycads and insects.

The discovery came in the form of an ancient boganiid beetle preserved in Burmese amber for an estimated 99 million years along with grains of cycad pollen. The beetle also shows special adaptations, including mandibular patches, for the transport of cycad pollen.

"Boganiid beetles have been ancient pollinators for cycads since the Age of Cycads and Dinosaurs," says Chenyang Cai, now a research fellow at the University of Bristol. "Our find indicates a probable ancient origin of beetle pollination of cycads at least in the Early Jurassic, long before angiosperm dominance and the radiation of flowering-plant pollinators, such as bees, later in the Cretaceous."

When Cai's supervisor Diying Huang at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, first showed him the beetle trapped in amber, he was immediately intrigued. He recognized that its large mandibles with bristly cavities might suggest the beetle was a pollinator of cycads.

After cutting, trimming, and polishing the specimen to get a better look under a microscope, Cai's excitement only grew. The beetle carried several clumps of tiny pollen grains. Cai consulted Liqin Li, an expert in ancient pollen at the Chinese Academy of Sciences, who confirmed that the pollen grains belonged to a cycad.

The researchers also conducted an extensive phylogenetic analysis to explore the beetle's family tree. Their analysis indicates the fossilized beetle belonged to a sister group to the extant Australian Paracucujus, which pollinate the relic cycad Macrozamia riedlei. The finding, along with the current disjunct distribution of related beetle-herbivore and cycad-host pairs in South Africa and Australia, support an ancient origin of beetle pollination of cycads, the researchers say.

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Those fragrances you enjoy? Dinosaurs liked them first

Glandular laurel in amber.

The compounds behind the perfumes and colognes you enjoy have been eliciting olfactory excitement since dinosaurs walked the Earth amid the first appearance of flowering plants, new research reveals.

Oregon State University entomologist George Poinar Jr. and his son Greg, a fragrance collector, found evidence that floral scents originated in primitive flowers as far back as 100 million years ago as pollinator attractants -- a role they still play even though today's flowers also have colorful petals for luring pollinators.

"I bet some of the dinosaurs could have detected the scents of these early flowers," George Poinar said. "In fact, floral essences from these early flowers could even have attracted these giant reptiles."

The Poinars examined amber flowers from Burma, including the now extinct glandular laurel flower (Cascolaurus burmensis) and veined star flower (Tropidogyne pentaptera).

The research revealed that the flower-based chemical compounds that are the basis for the perfumes and colognes we use today have been providing olfactory excitement to pollinating insects and other animals since the mid-Cretaceous Period.

Without colorful petals, flowers from that period had to rely solely on scents to attract pollinators.

"You can't detect scents or analyze the chemical components of fossil flowers, but you can find the tissues responsible for the scents," said George Poinar, professor emeritus in the OSU College of Science.

The floral secretory tissues producing these scents include nectaries, glandular trichomes, eliaphores and osmophores.

Nectaries are glands that produce fragrances and sweet deposits that insects love. Glandular trichomes are hairs with cells that make and send out scented secretory products. Eliaphores are stalked aromatic oil glands. oOsmophores, also known as floral fragrance glands, are cell clusters specializing in scent emission.

The study also found that secretory tissues of these Cretaceous flowers are similar in structure to those of their modern descendants. That suggests modern and ancient flowers of the same lineages produced similar essences.

Some of flowers studied were even in the process of emitting compounds at the time they were engulfed by the tree resin that later became amber.

The study also included a milkweed flower (Discoflorus neotropicus) and an acacia flower (Senegalia eocaribbeansis) in 20- to 30-million-year-old Dominican Republic amber.

The anther glands on the fossil acacia flower were especially attractive to bees, one of which was fossilized while visiting the stamens. Today, honeybees are still visiting acacia flowers that have the same type of flora glands that existed in the ancient past.

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Plants can tell the time using sugars

The plant as a clock

A new study by an international team of scientists, including the University of Bristol, has discovered that plants adjust their daily circadian rhythm to the cycle of day and night by measuring the amount of sugars in their cells.

Plants, animals, fungi and some bacteria can estimate the time of day through their circadian rhythms.

These rhythms are regulated by an internal 'circadian clock', and how these clocks operate is a topic of importance for both agriculture and medicine. For example, changes in circadian rhythms have contributed to domestication of crops.

In the study published today, in the journal Current Biology, the research team involving the Universities of Bristol, Cambridge, Campinas, Sao Paulo and Melbourne has discovered a process that adjusts the timing of the plant body clock so that it stays in tune with the environment.

They found that sugars made from photosynthesis are sensed, and this leads to the plant falling into rhythm with changes in energy provision throughout the day.

Dr Antony Dodd of the University of Bristol's School of Biological Sciences, said: "Our findings show the first mechanism in plants that shifts the circadian rhythm backwards or forwards to synchronise it with the environment.

"The plant continuously measures the amount of sugar in the cells and uses this information to make the required adjustments."

Plants need circadian their rhythms to be correctly synchronised with the timing of day and night, so their activities are matched to the time of day.

For example, circadian rhythms control the time when plants grow, when their flowers open and release scent, and allow plants to carefully use energy reserves so they do not starve in the night.

Circadian rhythms also help plants to detect changes in the seasons, which is crucial to ensure our crops mature in the correct season.

Dr Dodd added: "This means that the discovery of a mechanism that synchronizes the plant body clock with the time in the environment has identified a new process that could be exploited in future to improve crop performance."

From Science Daily

Aphids manipulate their food

This is an aphid infestation of the stem close to the bud of a tansy.

Aphids -- who hasn't been bothered by these little insects at one time or another? Why do they reproduce on plants so successfully? These are among the questions that Professor Dr Caroline Müller and her research team are addressing at Bielefeld University's Faculty of Biology. They have found out that aphids are able to influence the quality of their food, and that this may enable them to construct a niche on their own host plants. Müller's research team is located in the Transregio Collaborative Research Centre 'NC3' that is studying animals and their 'individual niches. They have published their findings in the journal New Phytologist.

There are hundreds of different aphid species. They all feed on plant sap, known as phloem sap. The nutritional value of the phloem sap is determined by the sugar concentration and the concentration and composition of amino acids. Previously it was not known how the quality of plant sap changes in different plant parts after aphid infestation, how this change in quality influences the development of aphids, and how, in turn, the aphids can change the composition of the plant sap.

Müller and her team are the first to confirm that aphid infestation actually does change the composition of the plant sap depending on which aphid species is infesting which specific part of the plant. For example, infestation of the stem close to the bud with a certain aphid species changes the composition of sugar and organic acids in the sap. In contrast, infestation of the old leaves with another aphid species increases the concentration of amino acids. And a further phenomenon can also be ascertained: 'We were able to observe that the aphid species that developed best on the stem close to the bud and the other species that proliferated best on the old leaves each specifically increased the quality of the plant sap of the corresponding plant part,' says Ruth Jakobs, a research assistant at the Faculty of Biology. Hence, aphids construct their own niche in such a way that they are able to profit from it. 'We can assume that aphids behave in a similar way to, for example, beavers that settle in the dams they have constructed themselves,' says Müller.

The biologists gained their findings by placing aphids on different parts of common tansy plants -- the stem close to the bud, a young leaf, and an old leaf -- and determining the growth of the populations of these insects at these locations. In addition, the biologists collected the plant sap and analysed its chemical composition.

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Invasive plants adapt to new environments

Invasive monkeyflowers growing among native forget-me-nots illustrate the assimilation of a non-native species 200 years after its introduction into the British Isles.

Invasive plants have the ability to adapt to new environments -- and even behave like a native species, according to University of Stirling research.

A study has found that the behaviour of invasive plants changes over time -- meaning plants of the same species act differently if they arrive in their new environment at separate times.

Scientists studied the characteristics of monkeyflowers (Mimulus guttatus), which first arrived in the UK from North America 200 years ago. They compared the behaviour of monkeyflowers long-established in Scotland with those introduced recently for the purposes of the experiment.

Significantly, they found that the long-established plants were bigger and produced more flowers and more clones than those recently introduced. In comparison, the study showed that the genes of plants recently introduced are not well-adapted to deal with the UK environment.

Dr Mario Vallejo-Marin, Associate Professor in the Faculty of Natural Sciences, led the work alongside PhD student Pauline Pantoja.

"Our study shows that invasive plants -- in this case, the monkeyflower -- become increasingly adapted to new environments thanks to natural selection," he explained.

"If we compare monkeyflowers that have been here for the last 200 years with those from North America today, they are completely different plants. It appears that, over time, the plants seem to become natives of their new home.

"In other words, these results suggest that invasive populations of plants are better suited to live in their new home than new arrivals from the native range."

The team created two types of hybrid plants -- a UK/North American hybrid and a UK/UK hybrid -- and grew them, under identical circumstances, to estimate the impact of natural selection. Over two years, around 1,200 plants were grown in a field plot at Stirling.

"The main differences seem to be that the UK plants can produce both high numbers of flowers and high numbers of clones while the hybrids created from the North American samples can only do either many flowers or many clones but not both," Dr Vallejo-Marin said.

Reflecting on the findings, he added: "The last 500 years have seen a rapidly increasing spread of non-native organisms around the world.

"Our study shows that, in older invasions -- more than 200 years old -- the newcomers are becoming adapted to their new surroundings through evolution by natural selection.

"As more non-native species come of age, the role of natural selection in the success of non-native species will continue to increase."

Dr Vallejo-Marin is now planning further studies to discover how common the process is -- and he believes others may also benefit from the work.

"Understanding how organisms adapt to new environments is key in an era of rapid environmental change," he said. "Our study can also be of relevance to environmental managers dealing with biological invasions."

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The seed that could bring clean water to millions

(left) Unshelled M. oleifera seeds, (middle) shelled seeds, (right) crushed seeds before protein extraction.

According to the United Nations, 2.1 billion people lack access to safely managed drinking water services, the majority of whom live in developing nations.

Carnegie Mellon University's Biomedical Engineering and Chemical Engineering Professors Bob Tilton and Todd Przybycien recently co-authored a paper with Ph.D. students Brittany Nordmark and Toni Bechtel, and alumnus John Riley, further refining a process that could soon help provide clean water to many in water-scarce regions. The process, created by Tilton's former student and co-author Stephanie Velegol, uses sand and plant materials readily available in many developing nations to create a cheap and effective water filtration medium, termed "f-sand."

"F-sand" uses proteins from the Moringa oleifera plant, a tree native to India that grows well in tropical and subtropical climates. The tree is cultivated for food and natural oils, and the seeds are already used for a type of rudimentary water purification. However, this traditional means of purification leaves behind high amounts of dissolved organic carbon (DOC) from the seeds, allowing bacteria to regrow after just 24 hours. This leaves only a short window in which the water is drinkable.

Velegol, who is now a professor of chemical engineering at Penn State University, had the idea to combine this method of water purification with sand filtration methods common in developing areas. By extracting the seed proteins and adsorbing (adhering) them to the surface of silica particles, the principal component of sand, she created f-sand. F-sand both kills microorganisms and reduces turbidity, adhering to particulate and organic matter. These undesirable contaminants and DOC can then be washed out, leaving the water clean for longer, and the f-sand ready for reuse.

While the basic process was proven and effective, there were still many questions surrounding f-sand's creation and use -- questions Tilton and Przybycien resolved to answer.

Would isolating certain proteins from the M. oleifera seeds increase f-sand's effectiveness? Are the fatty acids and oils found in the seeds important to the adsorption process? What effect would water conditions have? What concentration of proteins is necessary to create an effective product?

The answers to these questions could have big implications on the future of f-sand.

Fractionation

The seed of M. oleifera contains at least eight different proteins. Separating these proteins, a process known as fractionation, would introduce another step to the process. Prior to their research, the authors theorized that isolating certain proteins might provide a more efficient finished product.

However, through the course of testing, Tilton and Przybycien found that this was not the case. Fractionating the proteins had little discernible effect on the proteins' ability to adsorb to the silica particles, meaning this step was unnecessary to the f-sand creation process.

The finding that fractionation is unnecessary is particularly advantageous to the resource-scarce scenario in which f-sand is intended to be utilized. Leaving this step out of the process helps cut costs, lower processing requirements, and simplify the overall process.

Fatty Acids

One of the major reasons M. oleifera is cultivated currently is for the fatty acids and oils found in the seeds. These are extracted and sold commercially. Tilton and Przybycien were interested to know if these fatty acids had an effect on the protein adsorption process as well.

They found that much like fractionation, removing the fatty acids had little effect on the ability of the proteins to adsorb. This finding also has beneficial implications for those wishing to implement this process in developing regions. Since the presence or absence of fatty acids in the seeds has little effect on the creation or function of f-sand, people in the region can remove and sell the commercially valuable oil, and still be able to extract the proteins from the remaining seeds for water filtration.

Concentration

Another parameter of the f-sand manufacturing process that Tilton and Przybycien tested was the concentration of seed proteins needed to create an effective product. The necessary concentration has a major impact on the amount of seeds required, which in turn has a direct effect on overall efficiency and cost effectiveness.

The key to achieving the proper concentration is ensuring that there are enough positively charged proteins to overcome the negative charge of the silica particles to which they are attached, creating a net positive charge. This positive charge is crucial to attract the negatively charged organic matter, particulates, and microbes contaminating the water.

This relates to another potential improvement to drinking water treatment investigated by Tilton, Przybycien, and Nordmark in a separate publication. In this project, they used seed proteins to coagulate contaminants in the water prior to f-sand filtration. This also relies on controlling the charge of the contaminants, which coagulate when they are neutralized. Applying too much protein can over-charge the contaminants and inhibit coagulation.

"There's kind of a sweet spot in the middle," says Tilton, "and it lies in the details of how the different proteins in these seed protein mixtures compete with each other for adsorption to the surface, which tended to broaden that sweet spot."

This broad range of concentrations means that not only can water treatment processes be created at relatively low concentrations, thereby conserving materials, but that there is little risk of accidentally causing water contamination by overshooting the concentration. In areas where exact measurements may be difficult to make, this is crucial.

Water Hardness

Water hardness refers to the amount of dissolved minerals in the water. Although labs often use deionized water, in a process meant to be applied across a range of real world environments, researchers have to prepare for both soft and hard water conditions.

Tilton and Przybycien found that proteins were able to adsorb well to the silica particles, and to coagulate suspended contaminants, in both soft and hard water conditions. This means that the process could potentially be viable across a wide array of regions, regardless of water hardness.

Tilton and Przybycien recently published a paper on this research, "Moringa oleifera Seed Protein Adsorption to Silica: Effects of Water Hardness, Fractionation, and Fatty Acid Extraction," in ACS Langmuir.

Overall, the conclusions that Tilton, Przybycien, and their fellow authors were able to reach have major benefits for those in developing countries looking for a cheap and easily accessible form of water purification. Their work puts this novel innovation one step closer to the field, helping to forge the path that may one day see f-sand deployed in communities across the developing world. They've shown that the f-sand manufacturing process displays a high degree of flexibility, as it is able to work at a range of water conditions and protein concentrations without requiring the presence of fatty acids or a need for fractionation.

Read more at Science Daily

Sweet potatoes didn't originate in the Americas as previously thought

A) Modern distribution of the sweet potato family (yellow line) and genus (white line). B) Fossil leaf of Ipomoea meghalayensis. C) Modern leaf of Ipomoea eriocarpa, showing similar size, shape and vein pattern.

Sweet potatoes may seem as American as Thanksgiving, but scientists have long debated whether their plant family originated in the Old or New World. New research by an Indiana University paleobotanist suggests it originated in Asia, and much earlier than previously known.

IU Bloomington emeritus professor David Dilcher and colleagues in India identified 57-milion-year-old leaf fossils from eastern India as being from the morning glory family, which includes sweet potatoes and many other plants. The research suggests the family originated in the late Paleocene epoch in the East Gondwana land mass that became part of Asia.

"I think this will change people's ideas," Dilcher said. "It will be a data point that is picked up and used in other work where researchers are trying to find the time of the evolution of major groups of flowering plants."

Previous fossil evidence had suggested the morning glory family may have originated in North America about 35 million years ago. But molecular analyses had supported the idea that it originated earlier and in the Old World. The new research provides evidence for that conclusion.

The discovery also suggests the morning glory family and the nightshade family, which includes potatoes and tomatoes, diverged earlier than previously thought. Together with the recent, separate discovery of 52-million-year-old nightshade fossils in Argentina, it suggests that morning glories developed in the East and nightshades in the West.

The 17 fossils analyzed in the study are the earliest recorded fossils for both the morning glory family, known as Convolvulaceae, and the order Solanales, which includes morning glories and nightshades. Morning glory fossils are rare because the plants' soft structure was not easily preserved in rocks.

Dilcher's collaborators, Gaurav Srivastava and Rakesh C. Mehrotra of India's Birbal Sahni Institute of Palaeosciences, discovered the fossils in Meghalaya, a state in northeastern India.

The researchers used microscopic analysis of the shape and structure of the leaves, comparing details of the leaf veins and cells with plants in the genus Ipomoea. Using such analysis to examine evolutionary relationships has been a hallmark of Dilcher's paleobotany research career.

The leaves the researchers studied are in the genus Ipomoea, which includes sweet potato but also hundreds of other plants, most of which don't produce food for humans.

"We don't know that these were sweet potatoes," said Dilcher, emeritus professor in the Department of Earth and Atmospheric Sciences and the Department of Biology in the IU Bloomington College of Arts and Sciences. "We can't say there were delicious sweet potatoes there. There may have been, or there may not."

Read more at Science Daily

When did flowers originate?

When did flowering plants originate?

Flowering plants likely originated between 149 and 256 million years ago according to new UCL-led research.

The study, published today in New Phytologist by researchers from the UK and China, shows that flowering plants are neither as old as suggested by previous molecular studies, nor as young as a literal interpretation of their fossil record.

The findings underline the power of using complementary studies based on molecular data and the fossil record, along with different approaches to infer evolutionary timescales to establish a deeper understanding of evolutionary dynamics many millions of years ago.

"The discrepancy between estimates of flowering plant evolution from molecular data and fossil records has caused much debate. Even Darwin described the origin of this group as an 'abominable mystery'," explained lead author, Dr Jose Barba-Montoya (UCL Genetics, Evolution & Environment).

"To uncover the key to solving the mystery of when flowers originated, we carefully analysed the genetic make-up of flowering plants, and the rate at which mutations accumulate in their genomes."

Through the lens of the fossil record, flowering plants appear to have diversified suddenly, precipitating a Cretaceous Terrestrial Revolution in which pollinators, herbivores and predators underwent explosive co-evolution.

Molecular-clock dating studies, however, have suggested a much older origin for flowering plants, implying a cryptic evolution of flowers that is not documented in the fossil record.

"In large part, the discrepancy between these two approaches is an artefact of false precision on both palaeontological and molecular evolutionary timescales," said Professor Philip Donoghue from the University of Bristol's School of Earth Science, and a senior author of the study.

Palaeontological timescales calibrate the family tree of plants to geological time based on the oldest fossil evidence for its component branches. Molecular timescales build on this approach, using additional evidence from genomes for the genetic distances between species, aiming to overcome gaps in the fossil record.

"Previous studies into molecular timescales failed to explore the implications of experimental variables and so they inaccurately estimate the probable age of flowering plants with undue precision," said Professor Ziheng Yang (UCL Genetics, Evolution & Environment) and senior author of the study.

"Similarly, interpretations of the fossil record have not fully recognised its shortcomings as an archive of evolutionary history, that is, that the oldest fossil evidence of flowering plants comes from very advanced, not primitive flowering plant lineages," Professor Donoghue added.

The researchers compiled a large collection of genetic data for many flowering plant groups including a dataset of 83 genes from 644 taxa, together with a comprehensive set of fossil evidence to address the timescale of flowering plant diversification.

Read more at Science Daily

An integrated assessment of vascular plants species of the Americas

Tropical forest.

Missouri Botanical Garden researcher Dr. Carmen Ulloa is the lead author of "An Integrated Assessment of Vascular Plant Species of the Americas," published today in Science. Ulloa along with 23 co-authors compiled a comprehensive, searchable checklist of 124,993 species, 6,227 genera and 355 families of vascular plants of the Americas. This represents one third of all known vascular plants worldwide.

Establishing a checklist like this one has long been a goal of the Garden. In 2015, Ulloa started to research what already existed among existing Garden projects and other botanical institutions across the Americas. She then contacted the editors of the 12 major projects in the last 25 years that served as the basis for this larger checklist including the checklists of Bolivia, Brazil, Colombia, Ecuador, the Guianas, Mexico, Peru, the Southern Cone (Argentina, Chile, Paraguay, Uruguay), Venezuela, and the West Indies. Two partially published datasets of the Flora of North America North of Mexico and the Flora Mesoamericana were also used.

The Garden's plant database, Tropicos® was used as the projects data repository for the project. In the process, more than 25,000 names were added to Tropicos before a final list was compiled.

"This is the first time we have a complete overview of the plants of the Americas," said Ulloa. "It represents not only hundreds of years of plant collecting, and botanical research, but 6,164 botanists who described species that appear on this list. It is vital we have this information so that we know what each species is for conservation purposes."

Co-author Dr. Robert Magill first developed Tropicos in the early 1980s on tiny Osborne 01 microcomputer. Today, it is the world's largest botanical database. It is accessed more 70 million times each year by researchers around the world. It is a link to the past, a digital version of 4.4 million specimens in the Garden's expansive Herbarium. It is also a link to the future, the basis of a larger project, the World Flora Online. The Missouri Botanical Garden and more than 40 other institutions are working to develop the World Flora Online with the goal of documenting all known plant life by 2020.

A number of co-authors are current or former members of the Missouri Botanical Garden research staff including Dr. Gerrit Davidse, Heather Stimmel, Dr. James Zarucchi, Dr. Peter Jørgensen, Magill and Garden President Emeritus Dr. Peter Raven. In addition to this, Dr. Tom Croat and Dr. Charlotte Taylor are both acknowledged in the study's supplemental material for having more than 400 described plant species on the Americas list.

Read more at Science Daily

Ancient peoples shaped the Amazon rainforest

Amazon rainforest in Tambopata reserve, Peru

We often think of the Amazon rainforest as a vast expanse of nature untouched by humans. But a new study in Science suggests that's not true -- in fact, today's rainforest is shaped by trees that were cultivated by indigenous peoples thousands of years ago.

"Some of the tree species that are abundant in Amazonian forests today, like cacao, açaí, and Brazil nut, are probably common because they were planted by people who lived there long before the arrival of European colonists," says Nigel Pitman, the Mellon Senior Conservation Ecologist at Chicago's Field Museum and a co-author of the study.

The team made the discovery by overlaying data from more than 1,000 forest surveys on a map of more than 3,000 archaeological sites across the Amazon. By comparing forest composition at varying distances from archaeological sites, the analysis generated the first Amazon-wide picture of how pre-Columbian peoples influenced Amazonian biodiversity. The study focused on 85 tree species known to have been domesticated by Amazonian peoples for food, shelter, or other uses over the last several thousand years. The researchers found that throughout the Amazon basin, these species were five times more likely to be common in mature upland forests than non-domesticated species. In some parts of the basin, domesticated species were found to be both more common and more diverse in forests closer to archaeological sites.

"That's even the case for some really remote, mature forests that we'd typically assumed to be pristine and undisturbed," says Pitman.

The finding promises to heat up a long-simmering debate among scientists about how thousands of years of human settlement in the Amazon basin have influenced modern-day patterns of Amazonian biodiversity. The immense size of Amazonian forests has historically hampered archaeological research and given the impression of an untouched landscape, but a large number of new archaeological sites have been discovered in recent years.

The team, made up by hundreds of ecologists and social scientists worldwide, was led by Carolina Levis, a PhD student at Brazil's National Institute for Amazonian Research and Wagenigen University and Research in the Netherlands. "For many years, ecological studies ignored the influence of pre-Columbian peoples on the forests we see today. We found that a quarter of these domesticated tree species are widely distributed in the basin and dominate large expanses of forest. These species are vital for the livelihood and economy of Amazonian peoples and indicate that the Amazonian flora is in part a surviving heritage of its former inhabitants," says Levis.

The study also pinpointed regions of the Amazon that today concentrate especially high diversities and large populations of domesticated species. Southwestern Amazonia, where large stands of Brazil nut trees remain a foundation of local residents' livelihoods, is one such example. Other regions showed fewer domesticated species, or a weaker relationship between domesticated species and archeological sites, highlighting the need for more research on the history of Amazonian settlement. The degree to which the recent history of Amazonian settlement has affected the distribution and abundance of domesticated species in the Amazon also remains to be studied.

While the small number of domesticated species used in the study was sufficient to reveal a strong human signal in modern forests, the authors point out that the signal may be even stronger than they documented, since hundreds of other Amazonian tree species were used by pre-Colombian peoples and also deserve study. Untangling the complex interplay of historical, environmental, and ecological factors structuring the 16,000-species Amazonian tree flora remains a focus of the team's work.

Read more at Science Daily

Distant species produce 'love child' fern after 60-million-year breakup

A delicate woodland fern discovered in the mountains of France is the love child of two distantly-related groups of plants that haven't interbred in 60 million years, genetic analyses show.

For most plants and animals, reuniting after such a long hiatus is thought to be impossible due to genetic and other incompatibilities between species that develop over time.

Reproducing after such a long evolutionary breakup is akin to an elephant hybridizing with a manatee, or a human with a lemur, said co-author Kathleen Pryer, who directs the Duke University Herbarium.

Led by Pryer and Carl Rothfels of the University of California, Berkeley, the study appears online today and in the March 2015 issue of the journal American Naturalist.

The pale green fern was found growing wild on a forest floor in the Pyrenees and eventually made its way to a nursery, where researchers plucked several fronds and extracted the DNA to pinpoint its parentage.

To their surprise, genetic analyses revealed that the fern was the result of a cross between an oak fern and a fragile fern -- two distantly related groups that co-occur across much of the northern hemisphere, but stopped exchanging genes and split into separate lineages some 60 million years ago.

"To most people they just look like two ferns, but to fern researchers these two groups look really different," Rothfels said.

Other studies have documented instances of tree frog species that proved capable of producing offspring after going their separate ways for 34 million years, and sunfish who hybridized after nearly 40 million years, but until now those were the most extreme reunions ever recorded.

"For most plant and animal species, reproductive incompatibility takes only a few million years at the most," Rothfels said.

The sex lives of ferns may help explain why divergent fern lineages remain compatible for so long, the researchers say.

Fern sex is no different from hanky panky in many other creatures in that it requires a union between sperm and eggs. But whereas many other plants rely on birds, bees or other animals to play matchmaker, all ferns need is wind and water.

Plants that require pollinators to reproduce may have a harder time rekindling the spark after calling it quits, especially if the animals they rely on to do the deed are picky about flower shape, size or other traits that may have changed over time.

"It's tempting to think that there's something special about flowering plants that gives them a competitive advantage, but these results raise a different possibility," Rothfels said.

Read more at Science Daily

Plant genetic advance could lead to more efficient conversion of plant biomass to biofuels

Plant geneticists including Sam Hazen at the University of Massachusetts Amherst and Siobhan Brady at the University of California, Davis, have sorted out the gene regulatory networks that control cell wall thickening by the synthesis of the three polymers, cellulose, hemicellulose and lignin.

The authors say that the most rigid of the polymers, lignin, represents "a major impediment" to extracting sugars from plant biomass that can be used to make biofuels. Their genetic advance is expected to "serve as a foundation for understanding the regulation of a complex, integral plant component" and as a map for how future researchers might manipulate the polymer-forming processes to improve the efficiency of biofuel production.

The three key components, found in plant tissues known as xylem, provide plants with mechanical strength and waterproof cells that transport water. Working in the model plant Arabidopsis thaliana, Hazen, Brady and colleagues explored how a large number of interconnected transcription factors regulate xylem and cell wall thickening. Results appeared in an early online edition Dec. 24 in Nature.

An invited commentary in the journal on the significance of this discovery points out that "understanding how the relative proportions of these biopolymers are controlled in plant tissue would open up opportunities to redesign plants for biofuel use."Hazen, Brady and colleagues'study identified hundreds of new regulators and offers "considerable insight," the authors say, "into the developmental regulation of xylem cell differentiation."

Specifically, using a systems approach to identify protein-DNA interactions, they screened more than 460 transcription factors expressed in root xylem to explore their ability to bind the promoters of about 50 genes known to be involved in processes that produce cell-wall components. Hazen says, "This revealed a highly interconnected network of more than 240 genes and more than 600 protein-DNA interactions that we had not known about before."

They also found that each cell-wall gene in the xylem regulatory network is bound by an average of five different transcription factors from 35 distinct families of regulatory proteins. Further, many of the transcription factors form a surprisingly large number of feed-forward loops that co-regulate target genes.

In other words, rather than a series of on-off switches that leads to an ultimate action like making cellulose, most of the proteins including regulators of cell cycle and differentiation bind directly to cellulose genes and to other transcription regulators. This gives plants a huge number of possible combinations for responding and adapting to environmental stress such as salt or drought, the authors point out.

Read more at Science Daily

It's the pits: Ancient peach stones offer clues to fruit's origins

As peach trees in the Niagara Region of Ontario give up the last of their fruit for the season, their ancestors halfway around the globe are clamouring for attention.

In a study published in PLOS ONE, Gary Crawford, a U of T Mississauga anthropology professor, and two Chinese colleagues propose that the domestic peaches enjoyed worldwide today can trace their ancestry back at least 7,500 years ago to the lower Yangtze River Valley in Southern China, not far from Shanghai. The study, headed by Yunfei Zheng from the Zhejiang Institute of Archeology in China's Zhejiang Province, was done in collaboration with Crawford and X. Chen, another researcher at the Zhejang Institute.

"Previously, no one knew where peaches were domesticated," said Crawford. "None of the botanical literature suggested the Yangtze Valley, although many people thought that it happened somewhere in China."

Radiocarbon dating of ancient peach stones (pits) discovered in the Lower Yangtze River Valley indicates that the peach seems to have been diverged from its wild ancestors as early as 7,500 years ago.

Archeologists have a good understanding of domestication -- conscious breeding for traits preferred by people- of annual plants such as grains (rice, wheat, etc.), but the role of trees in early farming and how trees were domesticated is not well documented. Unlike most trees, the peach matures very quickly, producing fruit within two to three years, so selection for desirable traits could become apparent relatively quickly. The problem that Crawford and his colleagues faced was how to recognize the selection process in the archeological record.

Peach stones are well represented at archeological sites in the Yangtze valley, so they compared the size and structure of the stones from six sites that spanned a period of roughly 5,000 years. By comparing the size of the stones from each site, they were able to discern peaches growing significantly larger over time in the Yangtze valley, demonstrating that domestication was taking place. The first peach stones in China most similar to modern cultivated forms are from the Liangzhu culture, which flourished 4,300 to 5300 years ago.

"We're suggesting that very early on, people understood grafting and vegetative reproduction, because it sped up selection," Crawford said. "They had to have been doing such work, because seeds have a lot of genetic variability, and you don't know if a seed will produce the same fruit as the tree that produced it. It's a gamble. If they simply started grafting, it would guarantee the orchard would have the peaches they wanted."

Crawford and his colleagues think that it took about 3,000 years before the domesticated peach resembled the fruit we know today.

"The peaches we eat today didn't grow in the wild," Crawford added. "Generation after generation kept selecting the peaches they enjoyed. The product went from thinly fleshed, very small fruit to what we have today. Peaches produce fruit over an extended season today but in the wild they have a short season. People must have selected not only for taste and fruit size, but for production time too."

Discovering more about the origins of domesticated peaches tells us more about our human ancestors, too, Crawford noted.

Crops such as domesticated peaches indicate that early people weren't passive in dealing with the environment. Not only did they understand grain production, but the woodlands and certain trees were being manipulated early on.

Read more at Science Daily

Fantastically Wrong: The Strange History of Using Organ-Shaped Plants to Treat Disease

According to the doctrine of signatures, plants and nuts and vegetables that resemble a human body part or organ must be divined by God to treat said limb or organ. Thus should a walnut fix your brain if it gets too wrinkled … or something.

It’s hard to imagine being the first human being to look at a plant like, say, a stinging nettle and think, “I probably shouldn’t eat this, on account of the general agony it would cause me. But what if I cooked it first?” So you prepare it and nervously drop it down your gullet—and luckily enough, it turns out to be edible. But what if it hadn’t been? And what if there wasn’t a decent gastroenterologist nearby?

For tens of thousands of years before modern medicine, choosing plants that not only wouldn’t kill you, but could cure you of ills was an exercise in trial and error. So wouldn’t it be nice if nature (or God, who I guess would also be nature in a way) dropped hints as to which ones were good for the human body? Such thinking, known as the doctrine of signatures, actually developed with remarkable frequency all around the world from culture to culture. Plants meant to heal certain organs and body parts, like the liver or the eye, must show a certain “signature” by resembling the thing they treat.

So the bloodroot, with its red extract, was theorized to fix problems with blood. And the saxifrage, which breaks apart rocks as it grows, must relieve kidney stones. Venomous bites are covered too: Alkanet’s viper-shaped seeds help for snake bites, and the coiled shoots of the herb scorpius will take care of that scorpion sting lickety-split. Even using plants that grow in the same area where a disease like malaria is prevalent can be used as cures.

A 1923 reconstruction of an illustration from Giambattista Della Porta’s Phytognomonica of 1608. Eyebright, according to the doctrine of signatures, resembles the human eye and must therefore be effective at treating eye infections. But only if the eye is still in your head, not floating around disembodied like these ones.

We now know that this is both wildly wrong and wildly dangerous. A sliced mushroom may look like an ear, but that doesn’t mean you should eat it to cure your earache (choose the wrong mushroom and you can add 24 hours of talking to furniture to your troubles). But as we shall see, the doctrine of signatures, when properly applied, has in fact been for some cultures an indispensable tool in medicine.

Long before the theory popped up in the West, peoples all over the world subscribed to what we now call the doctrine of signatures, from Asia to the New World. Native American tribes all used it, according to Bradley C. Bennett in his essay “Doctrine of Signatures: An Explanation of Medicinal Plant Discovery or Dissemination of Knowledge?” The Cherokee, for instance, thought the common purslane’s stalks, which resemble worms, could be used to treat worms in humans.

In the West the doctrine was first mentioned in the writings of Pliny the Elder, the brilliant Roman naturalist whose imagination nevertheless often outpaced his grounding in reality. In the 1500s, German-Swiss physician Paracelsus wrote at length on the topic, claiming that “the soul does not perceive the external or internal physical construction of herbs and roots, but it intuitively perceives at once their Signatum.”

The 16th-century physician Paracelsus wrote extensively on the doctrine of signatures, apparently in a teeny-tiny notebook.

During the 16th and 17th centuries, the doctrine of signatures was ubiquitous in the West. According to Bennett, the view was a decidedly theological one: God, in all his/her benevolence, shapes certain plants to resemble human organs as a clue, and we need to take the hint. And if you don’t take the hint, well, God will force it on you. In Milton’s Paradise Lost, first published in 1667, the Archangel Michael uses the eyebright flower to cure Adam’s eye infection.

And there was the British botanist William Coles, writing a decade before that epic poem: “Though Sin and Satan have plunged mankinde into an Ocean of Infirmities, yet the Mercy of God, which is over all his workes, maketh Grasse to grow upon the Mountaines and Herbes for the use of men, and hath not only stamped upon them a distinct forme but also hath given them particular Signatures whereby a man may read the use of them.”

This theological grounding is quite problematic, in the sense that it assumes the universe was created for humankind, then stocked with convenient medicines for the taking, the kind of anthropocentric worldview also manifested in the geocentrism that Copernicus overthrew in the 16th century. There’s also the rather glaring issue of subjectivity: That root may look like a kidney to you, but it sure looks a lot like a liver to me.

Not that he needed to disprove the theory, but in his essay Bennett presents the findings of his research into the efficacy of various plants with heart-shaped leaves in treating heart disease. Searching various databases, he found 2,584 plants with such a shape, and randomly selected 80. Of those 80, only 21 were used in medicine, and of those only three applied specifically to cardiac medicine. “These data clearly refute any a priori value of heart-shaped leaves as signs for cardiac activity,” he writes. Translation: Don’t go around eating morning glory leaves to try to cure your heart murmurs.

The Archangel Michael, at left, was an early proponent of both sweet perms and the doctrine of signatures, using eyebright to restore Adam’s eyesight in Paradise Lost. Also, that kid is about to find out the hard way that pet fish don’t survive too good when walked on leashes.

And even in the heyday of the doctrine of signatures there were plenty of detractors. The 16th century Flemish physician Rembert Dodoens called it “absolutely unworthy of acceptance.” Even Samuel Hahnemann, who founded the practice of homeopathy, vehemently attacked the doctrine, which would turn out to be just as epically wrong as his own theory. He said in 1825 with an irony so hilarious it’s almost incomprehensible: “I shall spare the ordinary medical school the humiliation of reminding it of the folly of those ancient physicians who, determining the medicinal power of crude drugs from their signature, that is, from their color and form, gave the testicle-shaped Orchitis-root in order to restore manly vigour…”

Hahnemann and Dodoens were right, of course. But there is the problem of these supposed cures that … uh … actually work. The doctrine of signatures, it turns out, isn’t totally worthless bunk. The Cherokee’s worm-like purslane, writes Bennett, is indeed “effective in controlling intestinal parasite loads and has gastroprotective activity.” And the Archangel Michael’s eyebright, he adds, can be loaded into eye drops to treat infections of the peepers.

This orchid is good for those times when half of your penis falls off.

This could be coincidence, sure. But more likely it’s the fact that the doctrine of signatures has at times not been used to identify cures, but to remember them, and in that way has been quite beneficial for peoples without a written language. Where the vast majority of scholars have roundly dismissed the doctrine as silly pseudoscience, Bennett sees the mnemonic benefits of the theory. That is, its use as a device to memorize what plants can repair what problems in the human body.

He cites another scholar, writing in 2002 about the medicine of the native Peruvian peoples: “In these and other orally transmitted systems of thought, mnemonic cues may be essential to the viability of knowledge transmission. Plants that are both efficacious and easy to remember are more likely to be maintained in the pharmacopoeia of non-literate societies through time.”

In Europe, too, the doctrine of signatures was often applied after the plant’s efficacy had already been established. Bennett relates, for instance, the story of the discovery of willow bark’s powers. A reverend by the name of Edward Stone had accidentally tasted it, and found that its bitterness was much like that of cinchona bark, used to treat malaria. He then discovered that the willow could also be used to treat fevers, malarial or otherwise. And this, he concluded, is because the willow “delights in a moist and wet soil,” an environment where malaria is common. Cures, he reasoned, must occur near their causes.

Read more at Wired Science

Computer rendering: Graduate student brings extinct plants 'back to life'

Jeff Benca is an admitted über-geek when it comes to prehistoric plants, so it was no surprise that, when he submitted a paper describing a new species of long-extinct lycopod for publication, he ditched the standard line drawing and insisted on a detailed and beautifully rendered color reconstruction of the plant. This piece earned the cover of March's centennial issue of the American Journal of Botany.

Benca described this 400-million-year-old fossil lycopod, Leclercqia scolopendra, and created a life-like computer rendering. The stem of the lycopod is about 2.5 millimeters across.

"Typically, when you see pictures of early land plants, they're not that sexy: there is a green forking stick and that's about it. We don't have many thorough reconstructions," said Benca, a graduate student in the Department of Integrative Biology and Museum of Paleontology at UC Berkeley. "I wanted to give an impression of what they may have really looked like. There are great color reconstructions of dinosaurs, so why not a plant?"

Benca's realistic, full-color image could be a life portrait, except for the fact that it was drawn from a plant that lay flattened and compressed into rock for more than 375 million years.

Called Leclercqia scolopendra, or centipede clubmoss, the plant lived during the "age of fishes," the Devonian Period. At that time, lycopods -- the group Leclercqia belonged to -- were one of few plant lineages with leaves. Leclercqia shoots were about a quarter-inch in diameter and probably formed prickly, scrambling, ground-covering mats. The function of Leclercqia's hook-like leaf tips is unclear, Benca said, but they may have been used to clamber over larger plants. Today, lycopods are represented by a group of inconspicuous plants called club mosses, quillworts and spikemosses.

Both living and extinct lycopods have fascinated Benca since high school. When he came to UC Berkeley last year from the University of Washington, he brought a truckload of some 70 different species, now part of collections at the UC Botanical Garden.

Now working in the paleobotany lab of Cindy Looy, Berkeley assistant professor of integrative biology, Benca continues to establish a growing list of living lycopod species, several of which will eventually be incorporated into the UC and Jepson Herbaria collections.

Visualizing plant evolution

Benca and colleagues wrote their paper primarily to demonstrate a new technique that is helping paleobotanists interpret early land plant fossils with greater confidence. Since living clubmosses share many traits with early lycopods, the research team was able to test their methods using living relatives Benca was growing in greenhouses.

Early land plant fossils are not easy to come by, but they can be abundant in places where rocks from the Devonian Period form outcrops. But a large portion of these are just stem fragments with few diagnostic features to distinguish them, Benca said.

Read more at Science Daily

Unique chromosomes preserved in Swedish fossil

Researchers from Lund University and the Swedish Museum of Natural History have made a unique discovery in a well-preserved fern that lived 180 million years ago. Both undestroyed cell nuclei and individual chromosomes have been found in the plant fossil, thanks to its sudden burial in a volcanic eruption.

The well-preserved fossil of a fern from the southern Swedish county of Skåne is now attracting attention in the research community. The plant lived around 180 million years ago, during the Jurassic period, when Skåne was a tropical region where the fauna was dominated by dinosaurs, and volcanoes were a common feature of the landscape. The fossilised fern has been studied using different microscopic techniques, X-rays and geochemical analysis. The examinations reveal that the plant was preserved instantaneously, before it had started to decompose. It was buried abruptly under a volcanic lava flow.

"The preservation happened so quickly that some cells have even been preserved during different stages of cell division," said Vivi Vajda, Professor of Geology at Lund University.

Thanks to the circumstances of the fern's sudden death, the sensitive components of the cells have been preserved. The researchers have found cell nuclei, cell membranes and even individual chromosomes. Such structures are extremely rare finds in fossils, observed Vivi Vajda.

"This naturally leads us to think that there must be more to discover. It isn't hard to imagine what else could be encapsulated in the lava flows at Korsaröd in Skåne," said Vivi Vajda.

Professor Vajda has carried out the study with two researchers from the Swedish Museum of Natural History, Benjamin Bomfleur and Stephen McLoughlin. The fern belonged to the family Osmundaceae, Royal Ferns. In modern times, royal ferns grow in the wild in Sweden and are also a common garden plant. Living representatives of this family are very similar in appearance to the Jurassic fossil, which suggests that only limited evolutionary change has taken place over the millennia. By comparing the size of the cell nuclei in the fossilised plant with its living relatives, the researchers have been able to show that the royal ferns have outstanding evolutionary stability.

"Royal Ferns look essentially the same now as they did during the Jurassic Period, and are therefore an excellent example of what we call a living fossil," said Vivi Vajda.

Professor Vajda has also dated the rocks surrounding the fossil by studying pollen and spores preserved in these rocks. Their analysis revealed that the lava flows are around 180 million years old, from the early Jurassic Period. These results have considerably refined previous radiometric dating conducted on nearby volcano cones. In addition, the research study shows that spores from royal ferns, as well as pollen from coniferous trees, including cypress and cycad, are found in large quantities in the volcanic rock. This is evidence of varied vegetation and a hot, humid climate at the time when the area was engulfed by a disastrous volcanic eruption.

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