On the Genus Euphorbia

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

Suspicion

I collect cacti and succulents. The more I collect plants, the more and more I become interested in taxonomic and phylogenetic relationships between them. Not just my own plants – all of them. Most recently, the genus Euphorbia has been on my mind. My favorite species are E. meloformis var. valida and E. horrida.

I’m mostly familiar with the succulent and cacti-looking euphorbia (they are not true cacti) and a few ornamental annuals. Sometimes I would come across a species that I could determine was a euphorbia; but in trying to identify exactly which species, I found countless possibilities within the genus. It seemed odd to me that a single genus could contain so many different forms.

Turns out, Euphorbia consists of over 1800 separate species. What?! That is an insanely high number! Only about 20 genera of plants contain over 1000 separate species. Euphorbia is the fourth most populated genus among all genera of plants.

That staggering number got me thinking: how can a single genus have so many different species? How has the classification worked that out? Has the genus been phylogenetically examined? There’s no way a genus can be so huge. You know what breeders and collectors can do with that much genetic material in a single genus? The man-made hybrids seem endless.

Euphorbia globosa in bloom

Taxonomy

In older taxonomic practices, morphological similarities were the primary method of grouping individuals together. While that is still a common practice today, phylogenetic testing is now an accessible tool for organizing species into related groups.

Organizations such as the Angiosperm Phylogeny Group (APG) have been doing this advanced scientific research – analyzing DNA, doing detailed dissection, etc. Ultimately, they organize plant taxonomy and systematics with greater detail, and examine plant relationships genetically – phylogenetics.

Analyzing genomes is much more expensive and time consuming than observing morphologies. Now, a mix of methods is used, but DNA sequencing has definitely changed the systematics game in a big way. As a result of the APG’s incorporation of widespread phylogenetic DNA analyses, their taxonomical classifications are quickly becoming the generally accepted classifications among plant taxonomists.

Since the inclusion of genetic testing, many plant orders, families, and genera have been reorganized, renamed, expanded, or shrunk.

Euphorbia

One of the identifying features of euphorbias are their very unique flowers. All species in the genus have a cyathium, an inflorescence exclusively produced by euphorbias. Lacking in true petals, sepals, or nectaries, monoecious euphorbia flowers possess only the most essential parts of reproduction. However, bracts, extra-floral nectaries, and other structures surrounding the reproductive parts of the flowers make them appear superficially different.

It would be very time consuming to sequence the DNA of every member of this genus to see where they all fit. Approximately 10% of the euphorbias have been phylogenetically examined, and they confirm the traditional morphological placement. How about that?

Interestingly, of the species genetically analyzed, some were subsequently placed into the genus Euphorbia after historically being considered members of other genera.

Euphorbia horrida and Euphorbia obesa

So? What’s that mean?

Species within the same genus when crossed can (but not always) produce viable offspring. Sometimes they don’t because of differences in pollinators, flowering times, or geographic location, which prevents hybridization. Clades within plant genera also can affect intra-genus reproduction. For example, hard maples won’t naturally hybridize with soft maples, despite both being in the genus Acer. Perhaps the case is similar between the groups within Euphorbia.

As a plant collector and cacti and succulent enthusiast, imagining the endless amounts of hybrids within a massive genus is a fancy idea to me. The APG’s confirming of the initial classifications of Euphorbia into a massive genus makes the idea of endless hybrids all the more real.

Additional guest posts by Jeremiah Sandler:

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Jeremiah Sandler lives in southeast Michigan, has a degree in horticultural sciences, and is an ISA certified arborist. Follow him on Instagram: @j.deepsea

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Cedar Confusion

This is a guest post by Jeremiah Sandler. Words by Jeremiah. Photos by Daniel Murphy (except where noted).

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What makes a cedar a cedar?

I recently asked this question to a professor of mine because I kept hearing individuals in the field refer to many different species as “cedars”. It was puzzling to me because, being the taxonomy-nerd that I am, most of these plants are in entirely different plant families but still called the same thing. Yes, sometimes common names overlap with one another regionally; avoiding that mix up is the purpose of binomial nomenclature in the first place! So, what gives?! Why are 50+ different species all called cedars?

This professor is a forester, not a botanist. He told me the word “cedar” describes the wood. Turns out, after some research and conversation, that’s all there was to it. As defined by Google, a cedar is:

Any of a number of conifers that typically yield fragrant, durable timber, in particular.

Cedar wood is a natural repellent of moths, is resistant to termites, and is rot resistant. A good choice of outdoor lumber.

I was hoping to find either a phylogenetic or taxonomic answer to what makes a cedar a cedar. I didn’t. Taxonomic relationships between organisms are one of the most exciting parts of biology. Thankfully, some solace was found in the research:

There are true cedars and false cedars.

True cedars are in the family Pinaceae and in the genus Cedrus. Their leaves are short, evergreen needles in clusters. The female cones are upright and fat, between 3 – 4 inches long. Their wood possesses cedar quality, and they are native to the Mediterranean region and the Himalayas.

False cedars are in the family Cupressaceae, mostly in the following genera: Calocedrus, Chamaecyparis, Juniperus, and Thuja. Their leaves are scale-y, fan-like sprays. Female cones are very small, about half an inch long, and remain on the tree long after seed dispersal. The bark is often both reddish and stringy or peely. Their wood possesses cedar quality. It is easy to separate them from true cedars, but less obvious to tell them from one another. These false cedars are native to East Asia and northern North America.

I couldn’t do away with the umbrella term “cedar.” Every naturalist can agree that one of the most pleasurable things while outdoors looking at plants is identifying them. I have set a new objective to correctly identify and differentiate between all of the cedars and false cedars, rather than simply calling them cedars. I guess I’m just fussy like that.

The Problem with ‘Yes’ Landscapes

This is a guest post by Jeremiah Sandler. Follow Jeremiah on Instagram @j.deepsea

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I don’t work for a landscape company, nor have I ever worked for one. The company I do work for contracts with these companies to do health care on their landscapes. For example, we scout for insects and diseases, spray pesticides when necessary, make recommendations of proper cultural practices, and fertilize.

Something has been bothering me for the past two years about the landscapes in metropolitan southeast Michigan. Both commercial and residential landscapes have at least two things in common: the same plants, and the same poor management of these plants. The clients have no idea they’re being ripped off.

The landscape companies I have experience with seem to think the homeowner is always right.

The ‘Yes’ Conversation

You want a Colorado blue spruce in humid Michigan? Sure, no problem. Let’s put six trees within 15 square feet. Don’t bother removing the cage and burlap. We also won’t tell you the massive expense you’ll pay in the future to spray fungicides on your spruce to keep it alive. If one dies, we’ll just replace it with the same plant.

You want a green hedge? Boxwoods or yews. They’ll be sheared multiple times a year by our crew of expert (and underpaid and exhausted) workers. At the first sign of new growth, we’ll be there mutilating your plants to ensure that they stay at right angles. You see all of those ripped apart, discolored leaves on your shrubs? Ignore that; plants are meant to be tamed into perfect geometry. Oh, that’ll be an extra charge to spray insecticides and fungicides.

Here’s a list of plants you can get to add to the monotony in your neighborhood: crabapple, hawthorn, cherry, honeylocust, blue spruce, oak, red maple, Japanese maple, pear, white pine, boxwood, yew, hydrangea, arborvitae, burning bush, and wax begonias.

Why is your hemlock tree neon yellow? We don’t know, let’s just replace it. Why is your Norway maple declining? Well, when we planted it, we kept the cage on its root ball, despite this tree having notorious girdling roots. Let’s get you a new one. Why are some of your shrubs rotting out? We left the soaker hoses on them for years and kept them running regularly. Yes we can spray all of your plants. We can kill everything before it’s a problem.

We’re the best landscapers in town! Our services are top of the line, and we guarantee your landscape will look exactly the same as your neighbor’s.

That’s a very sardonic, hypothetical conversation between a homeowner and a landscape company. A sensible company knows you don’t know best. As a homeowner, it is wise to heed the advice of a company’s horticulturist. Cost is always a consideration for the homeowner. However, the more expensive company is not always the highest quality. Here’s why.

So, you want a Colorado blue spruce?

A responsible company won’t let you plant a blue spruce in a place with wet springs and humid summers. They will tell you why it is not a good idea, and they will suggest alternatives. For example, a concolor fir (Abies concolor) looks similar to a blue spruce. They are resistant to needle cast diseases and cytospora canker, and they can tolerate southeast Michigan’s alkaline soils. In the long run, it is much cheaper to get the right plant in the right place.

You will pay more for your blue spruce because, not only are you paying for installation, you are paying to spray fungicides year after year to avoid having a skeleton in your yard. Companies know there is a likelihood of replacing your newly planted blue spruces, so you are charged for it.

We love boxwoods and so do you

Maybe you do like the classic, formal look of hedges. And maybe you do like the texture offered by a boxwood or yew. That’s fine. This is the problem I see literally every single day: over-shearing.

An appropriate cultivar selection is the answer. Cultivars and hybrids exist which only grow to x-amount tall and x-amount wide. Simply read the tag from the nursery. If your landscape company planted the proper plants the first time, they wouldn’t be able to charge you as much as they do to “maintain” them. The right plants in the right places need very little maintenance. I will concede, a few plants can tolerate being sheared. Once in a great while is acceptable; not three times a year.

Excessive shearing stresses out a plant. In fact, certain chemicals released by the open wounds of the leaves attract insects. Wet, exposed tissue serves as a breeding ground for fungi. Some of the problems your shrubs face are directly caused by the shearing itself.

PlantAmnesty, a website dedicated to stopping bad pruning practices states:

Any pruning book will explain that one prunes to open up the center of the plant, allowing air and light penetration to make the plant healthy. Shearing, on the other hand, creates a twiggy outer shell that gets ever denser and collects more deadwood and dead leaves every year, the opposite of a healthy condition. The results create the perfect protected place for pests and diseases, akin to locking up the house so the garbage can’t be removed. After many years, this treatment can lead to disease and general bad health without actually being a disease itself. If plants have mites and blights, bugs and mildews galore, how they were pruned may be the root of the problem.

Not to mention, the plant is spending all of its energy regrowing those leaves you continually cut off. There are correct ways to prune plants, and none of them include the excessive use of motorized shears. A plant grows to reach an equilibrium with its environment. If the environment is adequate, the plant will grow. If the environment is unfavorable, the plant will decline. In other words, if it is growing, let it grow!

What’s a monoculture?

There seems to be only 15 plants which are acceptable to the landscaper. The plant selection is predictable. Certainly there are more than 15 different species of plants you can have on your property. Sure, some redundant species are okay: white pines, oaks, maples (except that damned Norway maple). I don’t want to discourage people from exploring new options, though.

Native plants offer easy beauty. They have evolved in your region for millennia and are therefore adapted to your environmental conditions. These plants often tolerate both biological and environmental stressors better than non-native plants. Expenses are saved when you don’t have to pay for disease control. You wouldn’t buy a vehicle, for example, that you know would break down and require fixing all the time.

There are dozens of other shrub options for texture, winter interest, privacy walls, etc., that you don’t have to hire a crew to shear every month. Surprisingly, some large yucca species are hardy in colder zones, which offer a different texture. Red-twig dogwoods provide colorful winter interest; there are red, green, and yellow-stemmed cultivars. Coyote willow is native to southeast Michigan. It is a thin-leafed, rhizomatous Salix species which forms beautiful yellow walls in the fall. An entire, separate article can be written on the subject of alternatives. Just know there are plenty of species to choose from no matter where you live.

Ask, and you shall receive

This request comes from homeowners and is often fulfilled by companies: “Can’t you just spray it?” Granting this request is entirely wrong. One cannot, by law and by principle, go around as a pesticide desperado. You live in that environment. Why would you want pesticides in excess? Chemicals are used as a last resort and strictly on an as needed basis.

Appropriate timing, safety precautions, and proper insect identification are all legally required before insecticides can be applied. Some of the ‘yes’-type companies will comply with all uneducated (and sometimes unsafe) requests.

Some of the appointments I have with customers address very rudimentary horticultural problems. The homeowner’s concerns are legitimate. Most problems they are having, though, can be avoided with an ounce of foresight. Issues include planting hemlock trees in full sun, or replacing a Japanese maple killed by verticillium wilt with another Japanese maple. The list goes on…

Saying ‘No’

There’s a myriad of things that can go wrong in a landscape. It is an artificial environment containing plants which evolved continents apart. Plants often don’t have the capacity to combat pathogens that they are not exposed to in their native habitats, but certain issues are impossible to predict. There is a base knowledge one should have before making these kinds of decisions. The “customer is always right” philosophy doesn’t apply in this domain. You should have some creative influence on your landscape; it’s yours, after all. Spend the time in the nursery looking for interesting plants, make a list, and run it by your landscaper. If they say ‘yes’ to all of your choices, fire them. The people you hire cannot be too timid to tell you ‘no’ sometimes.

“Right plant, right place” is the mantra among plant health care technicians. We are the people who have to clean up the messes made by your landscapers. If your landscaper did their job with longevity in mind, I probably wouldn’t have much to do.

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?

Picture 2

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:

Confidential Carnivore

This is a guest post. Words and images by Jeremiah Sandler

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If you live in North America or Europe, chances are you have seen Dipsacus fullonum, commonly called teasel.  Its tall (up to 2 meters), spiky flower stalks with large purple flowers are easy to spot in low-lands, ditches, or along highways.  Since this prolific seeder’s introduction to North America from Europe, it has steadily increased its habitat to occupy nearly each region of the United States. Of course, like all plants, teasel has its preferences and is more frequent in some areas than in others.

dipsacus fullonum_jeremiah sandler

Teasel is an unassuming, herbaceous biennial.  It takes two years to complete its life cycle: First-year growth is spent as a basal rosette, and second-year growth is devoted to flowering.  Standard biennial, right?  As of 2011, an experiment was conducted on this plant that changed the way we see teasel, and possibly all other similar plants.

“Here we report on evidence for reproductive benefits from carnivory in a plant showing none of the ecological or life history traits of standard carnivorous species.” -Excerpt from the report titled Carnivory in the Teasel Dipsacus fullonum — The Effect of Experimental Feeding on Growth and Seed Set by Peter J.A. Shaw and Kyle Shackleton.

We all have favorite carnivorous plants, Venus flytraps, pitcher plants, sundews, etc.. Their showy traps and various means of attracting insects are all marvels of evolution in the plant kingdom.  These insectivorous plants evolved these means of nutrient acquisition in an answer to the lack of nutrients in their environment’s soil.  In some of these plants, there is a direct relationship between number of insects consumed and the size of the entire plant. In others, there is no such relationship.

The unassuming, biennial teasel can now join the ranks of carnivore, or protocarnivore.  It didn’t evolve in bogs or swamps where soil nutrients are depleted.  It has no relationship to the standard carnivorous species. It doesn’t have any flashy traps. In fact, it has no obvious traits which suggest it can gain nutrients from insects. Teasel’s carnivorous habits can be likened somewhat to the carnivorous habits of bromeliads; water gathered in their leaves traps insects.

In Shaw and Shackleton’s experiment (done in two field populations), maggots were placed in water gathered in the center of some first-year rosettes of teasel.  Other rosettes in the same population were left alone as controls.  Not surprisingly, the teasels which were ‘fed’ larvae did not change in overall size.  The size of the overwintering rosette did not offer any predictability towards the size of flower shoots for the coming year. However, something strange did happen:

“…addition of dead dipteran larvae to leaf bases caused a 30% increase in seed set and the seed mass:biomass ratio.”…“These results provide the first empirical evidence for Dipsacus displaying one of the principal criteria for carnivory”

Teasel has some physiology to absorb nutrients from other macroorganisms despite teasel evolving in an entirely different setting than typical carnivorous plants.  Teasel’s already proficient reproductive capacity is enhanced by using insects as a form of nutrients in a controlled setting.  

Many exciting questions have been raised by this experiment. How has this absorption mechanism come about, without the obvious use of lures or other structures to attract insects? And how does teasel maximize upon its own morphology in the wild, if at all?  What would the results be if these experiments were recreated on other similar species?

There are studies being conducted all the time that further the boundaries of what we know about these stationary organisms. There are new discoveries waiting just around the corner. Carnivory in plants is amazing because it transcends common notions about plants; especially in the case of the unassuming teasel.

Selected Resources:

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Jeremiah Sandler lives in southeast Michigan where he works in the plant health care industry. He has a degree in horticultural sciences and is an ISA certified arborist. He is interested in all things plant related and plans to own a horticulture business where he can share his passion with others. Follow Jeremiah on Instagram: @j.deepsea

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