Tufty’s Plight, or Saving the U.K.’s Red Squirrel

“There is the great blank area where no red squirrels have returned, and this is where the grey ones first spread and are now permanent inhabitants. Outside it there are plenty of red squirrel populations still, though they have fluctuated, often severely.” — Charles Elton, The Ecology of Invasions by Animals and Plants, 1958

Sciurus vulgaris, or the Eurasian red squirrel, is widespread throughout northern Europe and east into Siberia. It is a small squirrel with a chestnut top and a creamy underside that spends much of its time in the tops of trees. Its tail is large and fluffy, and its ears are adorned with prominent tufts of hair. It enjoys a broad range of foods from seeds, fruits, and leaves to fungi, insects, and birds’ eggs. It is beloved in the United Kingdom, where its survival is being threatened by a North American cousin. This cousin, now established in the U.K. for well over a century, looks to increase its range across Europe, with a growing population in Italy and the potential to spread to neighboring countries.

Eurasian red squirrel (Sciurus vulgaris) - photo credit: wikimedia commons

Eurasian red squirrel (Sciurus vulgaris) – photo credit: wikimedia commons

Sciurus carolinensis, or Eastern gray squirrel, is native to eastern North America but has been introduced to parts of western North America as well as other parts of the world, including the United Kingdom, Italy, South Africa, and Australia. Its fur is typically dark to pale gray with red tones. It prefers mature forests where food and shelter are abundant; however, it is a highly adaptable species and is common in urban areas and disturbed sites. It shares habitat requirements with the red squirrel, but has the advantages of being larger, stronger, and able to digest acorns.

Gray squirrels were first introduced to the U.K. in 1876. Wealthy collectors were enchanted by them and began releasing them on their estates. The first pair made it to Ireland in 1911. Around this time biologists were becoming concerned by how quickly they were spreading as well as the damage they were doing to young trees and the effect they seemed to be having on red squirrel populations. The U.K. Parliament responded in 1937 by banning the possession and introduction of gray squirrels. In an article published in Science in June 2016, Erik Stokstad writes about this “troubling phenomenon: where gray squirrels established colonies, red squirrels sooner or later vanished.” The current population of red squirrels in the U.K. is estimated at around 140,000, while gray squirrels are thought to number more than 2.5 million.

Why red squirrels vanish when grey squirrels are present is not entirely understood. Competition for food is one factor. Grey squirrels seem to have an advantage over red squirrels in mixed deciduous forests, and according to Schuchert, et al. (Biological Invasions, 2014), after colonization by gray squirrels, red squirrels can become restricted to coniferous forests, which are “less favored by grey squirrels.”

But direct competition alone doesn’t explain the plummeting numbers of reds in the presence of grays. Another explanation was identified in 1981 – grey squirrels were spreading a disease. Several years of experimentation confirmed that red squirrels were dying of squirrelpox – a parapoxvirus that gray squirrels carry but show little or no sign of infection. The virus can spread quickly through a population of red squirrels, leaving them lethargic, malnourished, and an easy target for predators. Stokstad writes, “red squirrels are defenseless…as [they] succumb, gray squirrels quickly take over the habitat.

But not all grey squirrels carry the virus, and there are some regions where the virus isn’t a major problem. Habitat loss and fragmentation due to human development also plays a role in the red squirrel’s decline. Add to that, grey squirrels may be more inclined to live among humans, giving them an advantage over the more reclusive reds.

Efforts have been underway for decades now to reduce, and even eliminate, gray squirrels in the U.K. Tens of thousands of grey squirrels have already been trapped and killed, yet they continue to dominate. Schuchert et al. write, “while culling may decrease grey squirrel population size in the short term, their high dispersal abilities makes re-colonization likely.” Funding for culling programs isn’t always available, and protests from animal rights groups like Animal Aide U.K. and Animal Ethics also have an impact. One area that culling has proved successful is Anglesey, an island off the coast of Wales, where the red squirrel population had once been reduced to just 40 individuals. Schuchert et al. analyzed culling data over a 13 year period and determined that trapping and killing efforts “resulted in the sustained and significant reduction of an established grey squirrel population at a regional landscape scale.”

Eastern gray squirrel (Sciurus carolinensis) - photo credit: wikimedia commons

Eastern gray squirrel (Sciurus carolinensis) – photo credit: wikimedia commons

Red squirrels may also be experiencing some relief thanks to another threatened mammal. Martes martes, or the European pine marten, is a member of the weasel family and, as Stokstad writes, “a cat-sized predator [that] was nearly exterminated in the 20th century.” Hunting, both for fur and pest control, and habitat loss reduced pine marten numbers dramatically until it received legal protection in 1988. Since then it has started to rebound, particularly in Scotland and Ireland. Anecdotes suggested that pine marten recovery in these areas was resulting in fewer gray squirrels. A study published in Biodiversity and Conservation in March 2014 confirmed that gray squirrel populations in Ireland were at “unusually low density,” and that the increasing numbers of pine martens played a role in that. Gray squirrels move slower and spend more time on the ground compared to red squirrels, making them easier prey for pine martens.

Efforts are now underway to introduce pine martens to other parts of the U.K. where gray squirrel populations are problematic. However, according to Stokstad, “red squirrel advocates worry that the pine marten could be a false hope, promising a free and uncontroversial solution that could threaten funds for culling.”

Let’s remember that the gray squirrel was deliberately introduced to the United Kingdom by humans, and that human activity is one of the main reasons for the grey squirrel’s explosion and the red squirrel’s retreat. Culling is not likely to ever eliminate gray squirrels completely, yet no one wants to see red squirrels go extinct. Altered landscapes can favor certain species over others, so ensuring that there is plenty of favorable habitat available for the red squirrel is one way to aid its survival. The grays may be there to stay, but let’s hope a compromise can be found so generations to come can benefit from sharing space with the red squirrel (and perhaps the gray squirrel,too).

Tufty Fluffytail, a character developed to help teach kids road safety in the U.K., saves Willy Weasel from getting run over (again).

Red Squirrel Conservation Groups:

In Praise of Poison Ivy

This is a guest post by Margaret Gargiullo. Visit her website, Plants of Suburbia, and check out her books for sale on Amazon.

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No one seems to like Toxicodendron radicans, but poison ivy is an important plant in our urban and suburban natural areas. Poison ivy (Anacardiaceae, the cashew family) is a common woody vine, native to the United States and Canada from Nova Scotia to Florida, west to Michigan and Texas. It is also found in Central America as far south as Guatemala. It is all but ubiquitous in natural areas in the Mid-Atlantic United States. It has been recorded in over 70 wooded parks and other natural areas in New York City.

Leaflets of three? Let if be. Poison ivy (Toxicodendron radicans). photo credit: wikimedia commons

Leaflets of three? Let if be. Poison ivy (Toxicodendron radicans) – photo credit: wikimedia commons

Poison ivy does have certain drawbacks for many people who are allergic to its oily sap. The toxins in poison ivy sap are called urushiols, chemicals containing a benzene ring with two hydroxyl groups (catechol) and an alkyl group of various sorts (CnHn+1).

These chemicals can cause itching and blistering of skin but they are made by the plant to protect it from being eaten by insects and vertebrate herbivores such as rabbits and deer.

Poison ivy is recognized in summer by its alternate leaves with three, shiny leaflets and by the hairy-looking aerial roots growing along its stems. In autumn the leaves rival those of sugar maple for red and orange colors. Winter leaf buds are narrow and pointed, without scales (naked). It forms extensive colonies from underground stems and can cover large areas of the forest floor with an understory of vertical stems, especially in disturbed woodlands and edges. However, It generally only blooms and sets fruit when it finds a tree to climb. When a poison ivy stem encounters a tree trunk, or other vertical surface, it clings tightly with its aerial roots and climbs upward, reaching for the light (unlike several notorious exotic vines, it does not twine around or strangle trees). Once it has found enough light, it sends out long, horizontal branches that produce flowers and fruit.

Flowers of poison ivy are small and greenish-white, not often noticed, except by the honeybees and native bees which visit them for nectar and exchange pollen among the flowers. Honey made from poison ivy nectar is not toxic. Fruits of poison ivy are small, gray-white, waxy-coated berries that can remain on the vine well into winter. They are eaten by woodpeckers, yellow-rumped warblers, and other birds. Crows use poison ivy berries as crop grist (instead of, or along with, small stones) and are major dispersers of the seeds.

The fruits of poison ivy (Toxicodendron radicans) - photo credit: Daniel Murphy

The fruits of poison ivy (Toxicodendron radicans) – photo credit: Daniel Murphy

It is as a ground cover that poison ivy performs its most vital functions in urban and suburban woodlands. It can grow in almost any soil from dry, sterile, black dune sand, to swamp forest edges, to concrete rubble in fill soils, and along highways. It enjoys full sun but can grow just fine in closed canopy woodlands. It is an ideal ground cover, holding soil in place on the steepest slopes, while collecting and holding leaf litter and sticks that decay to form rich humus. It captures rain, causing the water to sink into the ground, slowing runoff, renewing groundwater, filtering out pollutants, and helping to prevent flooding.

Poison ivy is usually found with many other plants growing up through it – larger herbs, shrubs, and tree seedlings that also live in the forest understory. It seems to “get along” with other plants, unlike Japanese honeysuckle or Asian bittersweet, which crowd out or smother other plants. Poison ivy is also important as shelter for birds and many invertebrates.

While those who are severely allergic to poison ivy have reason to dislike and avoid it, Toxicodendron radicans has an important place in our natural areas. No one would advocate letting it grow in playgrounds, picnic areas, or along heavily used trail margins, but it belongs in our woods and fields and should be treated with respect, not hatred. Recognize it but don’t root it out.

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Further Reading: Uva, R. H., J.C. Neal and J. M. DiTomaso. 1997. Weeds of the Northeast. Comstock Publishing. Ithaca, NY.

This piece was originally published in the New York City Dept. of Parks & Recreation, Daily Plant.

Book Review: The New Wild

What if we were to look at invasive species with fresh eyes? Traditionally we have viewed them as interlopers hellbent on environmental destruction, but have we considered the good they can do? Should our efforts to eradicate them be tempered – eliminating them when it seems absolutely necessary, but accepting them when they are doing some good; welcoming them when they have something to offer. What does their presence mean anyway? What does it say about the ecosystems they inhabit and about us? Invasive species are convenient scapegoats, taking the blame for much of the ecological devastation that we started in the first place. Is that justified?

This is, essentially, the theme of The New Wild, a book by Fred Pearce that urges us to reconsider the ways we think, talk, and act towards invasive species. More than that, it is about dumping the idea that pristine nature (a mythological concept anyway, and one that is not all that useful) is the only true wild, and that nature invaded by alien species is a lesser thing that needs to be fixed. The truth is, nature is and always has been in a constant state of flux, and it is unconcerned about the provenance of the species that compose it. As Pearce puts it, if it’s doing “a useful job,” “it matters not a jot where a species comes from.”

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Invasion biology is a relatively new field of study, stemming from the publishing of Charles Elton’s book, The Ecology of Invasions by Animals and Plants, in 1958. For thousands of years, humans have had a hand in moving species of all kinds around the planet, but it was in the latter half of the 20th century that our awareness of the ecological damage that some of these species can do really developed. Since then we have made great efforts to remove such species and put things back the way we found them. The zeal with which we have done so hasn’t always been justified or effective, and throughout what at times has felt like an all out war against foreigners, a profound sense of animosity and suspicion towards anything non-native has taken root in our psyche.

Pearce hopes to mitigate these feelings and get us to reconsider some of our actions. To start with, he calls into question the distinction between aliens and natives: “A broad time horizon shows there is no such thing as a native species. All lodgings are temporary and all ecosystems in a constant flux, the victims of circumstance and geological accident.” Also, “many aliens are so well integrated that they are assumed to be native,” and “species come and go so much, as a result of both human and natural forces, that conventional hard distinctions about what belongs where have long been all but meaningless.”

Instead of judging a species by its provenance, “we should treat species on their merits and learn a little tolerance and respect for foreigners.” While “being alien can sometimes be problematic,” it can equally result in the renewal of “flagging ecosystems, creating new space for natives and providing ecosystem services.” Seeing that those services are in place is what should really matter, and “[ecological services] are best done by the species on hand that do it best.” After all, nature is not a system of “preordained perfection,” but instead “a workable mishmash of species, constantly reorganized by the throw of the dice.”

In his criticisms of the field of invasion biology, Pearce investigates some of the “constantly recycled ‘facts’ about alien species.” He finds many of the claims to be unfounded and oft-repeated statistics to be blatant misrepresentations of the original studies. He concludes that “some of the most widely used statistics in the canon of invasion biology do not stand up.” To support his point, he offers several examples of how alien species have added to the biodiversity in certain ecosystems and he shares stories that “show how we instinctively blame aliens for ecological problems that may have a lot more to do with our own treatment of nature.”

Immigrant Killers by Carolyn King, one of many books making a case for the war on alien species.

Immigrant Killers by Carolyn King, one of many books published in the past few decades that makes the case for waging war on alien species.

In so many words, Pearce’s stance is that the classic “aliens are bad, and natives are good” approach is outdated – “nature doesn’t care about conservationists’ artificial divide between urban and rural or between native and alien species,” which means that our perception of aliens should shift from being “part of the problem to part of the solution.” Abandoned farmlands, secondary forests, recolonized waste places, urban sprawl, and other novel ecosystems across the globe offer explicit examples of species from all backgrounds coming together to create functional habitats. This is the new wild.

Pearce is not advocating that we throw in the towel and let invasive species run rampant: “It would be foolish to claim that alien species never do any harm or that efforts to uproot them are always doomed to fail.” His support for the new wild is “not a call to let it rip.” Instead, “conservation in the twenty-first century requires an open-minded assessment of what might work – not a sullen retreat into blinkered orthodoxy.” So, rather than try to stop the flux of nature (an act that is decidedly “anti-nature”), let’s see where it goes, alien species and all; and when we do decide to beat back invasives and intervene “to preserve what we like,” we should be mindful that nature may be “traveling in a different direction.” As Pearce writes, “the new wild is flourishing, and it will do better if we allow it to have its head.”

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Obviously this is a controversial topic, but the ideas in this book are worth exploring further. Pearce’s notes are extensive, and I intend to read through many of his resources. Stay tuned for more posts. Meanwhile, you can listen to an interview with Pearce on this episode of Talking Plants. For a more critical veiw of Pearce’s book, check out these reviews by Los Angeles Review of Books and The EEB & Flow.

 

Introducing Invasive Species

The terms “invasive” or “invasive species” get thrown around a lot. They are frequently used to describe anything that is “misbehaving,” or acting in a way that doesn’t fit our idealized vision for how a landscape should look and function. Oftentimes a species that is introduced (by humans) or is not native to an area automatically gets labeled invasive, even if it isn’t acting aggressively or having any sort of dramatic impact on the ecosystem. It is an alien species in an alien environment; it has invaded, therefore it is invasive.

image credit: cartoon movement

image credit: cartoon movement

Determining what is actually invasive in what location and at what time is much more complex than that. We do our best to understand the natural features and functions of ecosystems, and we single out any species, whether introduced or not, that is acting to upset things. That species is considered invasive and, if the goal is to restore the natural balance, it must be controlled. To what degree a species should be controlled depends on the degree that it is upsetting things. Ultimately, it comes down to human judgement. Hopefully that judgement is based on the best available evidence, but that isn’t always the case.

But we are getting ahead of ourselves. What I mostly want to accomplish with this post is to introduce the concept of invasive species and point you to a selection of resources to learn more about them. I defined invasive species in a post I wrote back in August 2015, so I will repeat myself here:

“Invasive species” is often used inappropriately to refer to any species that is found outside of its historic native range (i.e. the area in which it evolved to its present form). More appropriate terms for such species are “introduced,” “alien,” “exotic,” “non-native,” and “non-indigenous.” The legal definition of an invasive species (according to the US government) is “an alien species that does or is likely to cause economic or environmental harm or harm to human health.” Even though this definition specifically refers to “alien species,” it is possible for native species to behave invasively.

These terms refer not just to plants but to all living organisms. The term “noxious weed,” on the other hand, is specific to plants. A noxious weed is a plant species that has been designated by a Federal, State, or county government as “injurious to public health, agriculture, recreation, wildlife, or property.” A “weed” is simply a plant that, from a human perspective, is growing in the wrong place, and any plant at any point could be determined to be a weed if a human says so.

Invasive species are easily one of the most popular ecological and environmental topics, and resources about them abound – some more credible than others. Here is a list of places to start:

That should get you started. There are, of course, numerous books on the subject, as well as a number of peer-reviewed journals dedicated to biological invasions. You should also be aware that IUCN maintains a list of the Top 100 World’s Worst Invasive Species and that there is a National Invasive Species Awareness Week, which is quickly approaching. This episode of Native Plant Podcast with Jamie Reaser (executive director of National Invasive Species Council) offers an informative discussion about invasive species, and a search for “invasive species” on You Tube brings up dozens of results including this brief, animated video:

 

I want to believe that we are doing the right thing when we make concerted efforts to remove invasive species and restore natural areas, but I’m skeptical. The reason why I have chosen to spend an indefinite amount of time exploring the topic of invasive species is because I truly want us to get it right. Yet I don’t even know that there is a “right.” It seems to me that there are endless trajectories – each one of them addressing different objectives and producing different outcomes. In a way we are playing God, regardless of which approach we take. We are making decisions for nature as if we know what’s best for it or that there even is a “best.”

Humans have had major impacts on virtually every square inch of the planet and have been placing our fingerprints on every ecosystem we touch since long before we became the humans we are today, and so it is difficult for me to envision a planet sans humans. It is also difficult for me to buy into the idea that our planet should look as though humans haven’t touched it (i.e. pristine). Because we have been touching it – for hundreds of thousands of years. Efforts to rewind time to before introductions occurred or to hold an ecosystem in stasis, securing life for only those species that “belong” there, seem noble yet fanciful at best and misguided, arrogant, and fruitless at worst.

To be the best conservationists we can be, we probably need to find a middle ground regarding invasive species – not a deter and eliminate at all costs approach, but also not a complete surrender/all are welcome and all can stay stance. Somewhere in between seems reasonable, acknowledging that the strategy taken will be different every time based on the location, the species in question, and our objectives. Of course, none of my beliefs or opinions on this topic (or any topic for that matter) are fully formed. I am trying to do my best to maintain an open mind, seeking out the best information available and following the evidence where it takes me. A topic as complex as invasion biology, however, is never going to be easy to finalize one’s opinions on, and so this journey will be boundless. I hope you will join me.

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Last but not least, here are two articles that discuss updating our approach to dealing with invasive species:

 

Our Urban Planet

As the human population balloons and cities sprawl, ecological studies in urban areas are following suit. Nature has always been a component of cities – we can’t escape it after all, as hard as we may try – but urban nature (and the enhancement of it) has become increasingly important as the human species continues to urbanize. More and more we are seeing the importance of melding the built environment with the natural one. Our motivations are diverse – albeit largely anthropocentric. But that’s fine. As we make improvements to the live-ability of cities for human’s sake, other living beings benefit. We are finding ways to get along with our neighbors, and we are learning to appreciate and value them as well.

Since 2008, the world’s urban population has outnumbered its rural population, and it is predicted that by 2050, more than two-thirds of humans will be urbanites. Immense resources are required to support such large, concentrated populations, and most of these resources are produced outside of urban areas. This results in an ecological footprint that is significantly larger than the city itself. Additionally, waste and pollution produced within cities negatively effects surrounding areas and beyond in abundant ways.

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In May of this year, Science put out a special issue entitled, “Urban Planet,” which features a series of articles that address some of the latest research in urban ecology and discuss current developments and future research needs – a sort of state of the union address for urban ecology in 2016. A series of 13 articles covered diverse topics including city-integrated renewable energy, innovative solutions to water challenges, transportation and air pollution, and food security in an urban world. Rodent-borne diseases in urban slums, creating sustainable cities in China, and Vancouver’s push to become the “greenest city” were also features of this special issue.

The issue serves to highlight the importance of this field of study and the urgency there is in finding solutions to major environmental challenges. But it also offers hope. Bright minds are working towards solutions to this century’s biggest problems as we look towards a more sustainable future. The introduction emphasizes that “the rise of cities is not…all doom and gloom.” Urbanization has upsides: “consolidating human populations helps shrink our individual environmental footprints, and cities are serving as living laboratories for further improvements.”

Urban ecology is a relatively recent subfield of ecology. In The Ecological Future of Cities, Mark McDonnell and Ian MacGregor-Fors describe how it “arose in the 1990’s out of a need to increase our…understanding of the ecological and human dimensions of urban ecosystems.” Initially the field was mainly concerned with biodiversity and the ecosystem processes and services found within cities. Findings from these studies are now influencing urban planning, design, and management. Such decisions are also informed by more recent studies in the field of urban ecology, which has grown to include “issues of sustainability, environmental quality, and human well-being in urban ecosystems.”

The authors note that our ecological understanding of cities was waylaid because “nature within cites was long considered unworthy of study, except when it involved solving environmental problems that threatened human well-being.” Cities were perceived as unnatural because humans had “disrupt[ed] the natural ecological conditions and processes that scientists [were] attempting to understand.” Today, ecologists recognize that studies in the field of urban ecology help us better understand basic ecological principles, while also providing “valuable information for creating liveable, healthy, and resilient urban environments.”

Studies in urban ecology have also increased our understanding of the mechanisms involved in evolution and adaptation. To illustrate this, the authors offer examples of birds that modified their songs “to communicate at noisy locations” and plants that shifted their seed dispersal strategies to survive in “highly fragmented urban habitats.” The authors also highlight the importance of maintaining or restoring natural vegetation in urban areas in order to help preserve struggling species of plants and animals, citing a study that found that “fewer local plant extinctions occurred in cities that maintained at least 30% native vegetation cover.” Additionally, the authors note that “the scope of urban ecology research extends well beyond city limits,” since urbanization is partly to blame for numerous environmental issues including habitat loss and fragmentation, biodiversity loss, climate change, and invasive species.

In Living in Cities, Naturally, Terry Hartig and Peter Kahn, Jr. address the topic of mental health and urban living. While there is still much to learn about the relationship between the two, it is generally believed that viewing or spending time in nature can help improve one’s mental well-being. As the authors put it, “parks and green spaces” can be viewed as “health resources for urban populations,” and including natural areas and natural processes in the design and creation of cities is necessary “for psychological as well as ecological purposes.”

Green roofs

Green roofs are one way to add green space to urban areas. They help replace vegetation that was removed when buildings were constructed, and they offer numerous environmental benefits.

Interacting with nature in an urban setting can help people develop positive feelings about the natural world and may encourage support for environmental protection. The authors worry that if future generations grow up without an intimate connection to the natural world, elevated amounts of environmental degradation will be seen as normal and a feeling of urgency to protect the environment from continued degradation will fade. This is why including plentiful amounts of green space within cities is essential: “Providing opportunities for people to experience more robust, healthy, and even wilder forms of nature in cities offers an important solution to this collective loss of memory and can counter the shifting baseline.”

This special issue of Science highlights some of the current ecological and environmental research regarding urbanization. For a great introductory look at urban ecology and basic ecological principles, check out the book, Nature All Around Us. Also, expect to see many more urban ecology themed posts on Awkward Botany. Tell your friends.

Thoughts on Equisetum Phylogenesis

This a guest post. Words and photos by Jeremiah Sandler.

These notes do not discuss either anatomy or medicinal uses of Equisetum. Both topics are worthy of their own discourse.

Plants in the genus Equisetum can be found on each continent of our planet, except for Antarctica. The plants are collectively referred to as scouring rush or horsetail.  Equisetum is in the division of plants called Pteridophytes, which contains all of the ferns and fern-allies (lycopods, whisk ferns, etc.) Pteridophytes are characterized by having a vascular system and by reproducing with spores, rather than seeds. Equisetum is the only living genus within the entire class Equisetopsida.  Within this single genus, there are a mere 20 species.

Picture 1

Equisetums can live pretty much anywhere. They can tolerate lots of shade, lots of sun, and virtually any soil condition (including submerged soil). Rhizomatous stems make it difficult for either disease or insects to kill an entire population. They do not require pollinators because they reproduce with spores.  Sounds like a recipe for reproductive and evolutionary success. Yet with all of these traits working in their favor, there is only a single genus left.  

Where’d they all go?

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Let’s briefly consider the origin of these plants first. In the late Paleozoic Era, during the end of the Cambrian Period, these plants began their takeover. Shortly thereafter (about 70 million years later), in the Devonian Period, land plants began to develop a tree-like habit, also called “arborescence.” Tree-sized ferns and fern-allies ruled the planet. They formed the ancient forests.

The elements required for photosynthesis were plentiful. The planet was warm. Competition from the Cambrian Explosion of flora and fauna drove plants upwards towards the sky. Larger plants can both shade their competition and remain out of reach of herbivores. None of the Equisetum species alive today are near their ancestors’ height.  

picture 3

It is rather obvious why we don’t see as many Equisetum species, and why they are not as large: The planet now is not the same planet it once was. Oxygen levels back in those times were about 15% higher than today’s levels. Seed plants can diversify much faster than non-seed-bearing plants; Equisetum cannot compete with the rate of diversification of seed-bearing plants.

The most interesting predicament comes when Equisetum is compared with other Pteridophytes. Some ancient Pteridophytes still do have diversity of genera. True Ferns, as they’re called, are broad-leaved ferns. In the class Filicopsida, there are 4 orders of True Ferns containing about 100 genera combined. Equisetum has 1 order and 1 genera.

What’s the primary difference between these two classes of Pteridophytes?  Broad leaves.

Most pteridophytes tolerate some shade; most other plants can’t tolerate as deep of shade as ferns. More specifically, the amount of shade the plants create could be a deciding factor in this question. True ferns have all of the traits equisetums have, with one additional physical trait that has pulled them ahead: Broad leaves allow true ferns to actively shade out local competition while creating more habitat for themselves. Equisetums don’t have this aggressive capacity.

Of course there are other biological and evolutionary pressures affecting equisetums beside their lack of broad leaves. The structure they do possess has benefited them at a time when it was advantageous to have it.  Otherwise why would it exist? Equisetums remind me of the dynamic nature of a planet. I don’t anticipate equisetums coming back. 

Although, I find it entertaining to humor the idea that they might return to their former glory. The planet’s climate could change toward any direction (I’m not a climatologist, though). Maybe equisetums are adequately prepared to adapt to whatever changes come – or maybe we are observing the gradual decline of an old branch on the tree of life.  

Resources:

Ethnobotany: Cattails

“If you ever eat cattails, be sure to cook them well, otherwise the fibers are tough and they take more chewing to get the starchy food from them than they are worth. However, they taste like potatoes after you have been eating them for a couple weeks, and to my way of thinking are extremely good.”  – Sam Gribley in My Side of the Mountain by Jean Craighead George

franz

Illustration by Franz Anthony (www.franzanth.com)

Ask anyone to list plants commonly found in American wetlands, and you can guarantee that cattails will make the list nearly every time. Cattails are widespread throughout the Northern Hemisphere. They are so successful, that it is hard to picture a wetland without them. In her book, Braiding Sweetgrass, Robin Wall Kimmerer discusses this well known association:

Cattails grow in nearly all types of wetlands, wherever there is adequate sun, plentiful nutrients, and soggy ground. Midway between land and water, freshwater marshes are among the most highly productive ecosystems on earth, rivaling the tropical rainforest. People valued the supermarket of the swamp for the cattails, but also as a rich source of fish and game. Fish spawn in the shallows; frogs and salamanders abound. Waterfowl nest here in the safety of the dense sward, and migratory birds seek out cattail marshes for sanctuary on their journeys.

The two most abundant species of cattails in North America are Typha latifolia (common cattail) and Typha angustifolia (narrow leaf cattail). T. angustifolia may have been introduced from Europe. The two species also hybridize to form Typha x glauca. There are about 30 species in the genus Typha, and they share the family Typhaceae with just one other genus. The common names for cattail are nearly as abundant as the plant itself: candlewick, water sausage, corn dog plant, cossack asparagus, reedmace, nailrod, cumbungi, etc., etc.

Cattails have long, upright, blade-like leaves. As they approach the base of the plant, the leaves wrap around each other to form a tight bundle with no apparent stem. As Kimmerer puts it, this arrangement enables the plants to “withstand wind and wave action” because “the collective is strong.” Flowers appear on a tall stalk that reaches up towards the tops of the leaves. The inflorescence is composed of hundreds of separate male and female flowers. Male flowers are produced at the top of the stalk and female flowers are found directly below them. In the spring, the male flowers dump pollen down onto the female flowers, and wind carries excess pollen to nearby plants, producing what looks like yellow smoke.

After pollination, the male flowers fade away, leaving the female flowers to mature into a seed head. Just like the flowers, the seeds are small and held tightly together, maintaining the familiar sausage shape. Each seed has a tuft of “hair” attached to it to aid in wind dispersal. In The Book of Swamp and Bog, John Eastman writes about the abundant seeds (“an estimated average of 220,000 seeds per spike”) of cattail: “A quick experiment, one that Thoreau delighted to perform, demonstrates how tightly the dry seeds are packed in the spike – pull out a small tuft and watch it immediately expand to fill your hand with a downy mass.”

cattails bunch

cattail fluff

Because cattails spread so readily via rhizomes, prolific airborne seeds mostly serve to colonize new sites, away from the thick mass of already established cattails. The ability to dominate vast expanses of shoreline gives cattails an invasive quality that often results in attempts at removal. Various human activities may be aiding their success. Regardless, they provide food and habitat to numerous species of insects, spiders, birds, and mammals. A cattail marsh may not be diverse plant-wise, but it is teeming with all sorts of other life.

Ethnobotanically speaking, it is hard to find many other species that have as many human uses as cattails. For starters, nearly every part of the plant is edible at some point during the year. The rhizomes can be consumed year-round but are best from fall to early spring. They can be roasted, boiled, grated, ground, or dried and milled into flour. Starch collected from pounding and boiling the rhizomes can be used as a thickener. In the spring, young shoots emerging from the rhizomes and the tender core of the leaf bundles can be eaten raw or cooked and taste similar to cucumber. Young flower stalks can be boiled and eaten like corn on the cob and taste similar to artichoke. Pollen, which is high in protein, can be mixed with flour and used to make pancakes and baked goods, among other things. The seeds can be ground into flour or pressed to produce cooking oil.

Cattail leaves can be used to make cords, mats, baskets, thatch, and many other things. Kimmerer writes about the excellent wigwam walls and sleeping mats that weaved cattail leaves make:

The cattails have made a suburb material for shelter in leaves that are long, water-repellent, and packed with closed-cell foam for insulation. … In dry weather, the leaves shrink apart from one another and let the breeze waft between them for ventilation. When the rains come, they swell and close the gap, making the [wall] waterproof. Cattails also make fine sleeping mats. The wax keeps away moisture from the ground and the aerenchyma provide cushioning and insulation.

The fluffy seeds make great tinder for starting fires, as well as excellent insulation and pillow and mattress stuffing. The dry flower stalks can be dipped in fat, lit on fire, and used as a torch. Native Americans used crushed rhizomes as a poultice to treat burns, cuts, sores, etc. A clear gel is found between the tightly bound leaves of cattail. Kimmerer writes, “The cattails make the gel as a defense against microbes and to keep the leaf bases moist when water levels drop.” The gel can be used like aloe vera gel to soothe sunburned skin.

Eastman rattles off a number of commercial uses for cattail: “Flour and cornstarch from rhizomes, ethyl alcohol from the fermented flour, burlap and caulking from rhizome fibers, adhesive from the stems, insulation from the downy spikes, oil from the seeds, rayon from cattail pulp, …” To conclude his section on cattails he writes, “With cattails present, one need not starve, freeze, remain untreated for injury, or want for playthings.”

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