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Pycnofibers? Or trichomes?

27 Dec

Pycnofibers and trichomes

Before dinosaurs and birds, other creatures like pterosaurs lived on the Earth. They didn’t have hair or feathers. But they had surface filaments on their bodies that can be seen in their fossils. The cellular structures are called ‘pycnofibers’. They had a single empty cylinder inside each filament. Pycnofibers arose from the epidermal cells, not from under the skin like hairs with their hair follicles. Nor like feathers. 

What amazes me, and which I find amusing, is that plants have these structures, too. They are called ‘trichomes’, and are well documented, including electron micrographs depicting the variety of trichome structures and shapes. Yet, nowhere in the literature that includes ‘pycnofibers’ is any mention of trichomes! Perhaps pycnofibers are the animal equivalent of the plant trichome. 

Trichomes can be inert with no chemical activity, or metabolic. Some are single-celled, some are multi-celled. Some are metabolic, some are secretory. Some are visible with the naked eye, others require a microscope. There is even a ‘trichom-ome’ now; the investigation of all the proteins and pathways involved in producing trichomes and their contents. Yet, the content of some trichomes is only air. And I am pretty sure that some of you have had encounters with trichomes. 

A trichome encounter

Last summer, while conducting a waterfowl breeding survey, I had an intimate


Trichomes on stinging nettle.

encounter with trichomes. The route for the survey was a walk-through on an unmowed dike dividing two marshes. Much of the vegetation – mustards, and other composite plants- was over my head at 5 feet plus four inches. The route was like pushing through jungle vegetation. One hand held my notebook and pencil and the other hand and arm pushed vegetation aside. 

Three-quarters on my way back to the starting point, my left hand and wrist began burning, like dozens of bites by fire ants. When I reached the vehicle, both hand and wrist were burning, red, and itching like crazy. Good thing I always wear long-sleeved shirts.

The culprit was the trichomes on stinging nettle plants. These tiny hair-like structures are on the stems and undersides of leaves. The thin outer portion of the trichome is silica, and it is very brittle. Shaped like a long hair with a fine point, the tip can break off and penetrate the skin of an animal that brushes up against it. When broken, a complex mixture of chemicals inside the trichome is dumped onto and into the skin. 

A chemical analyses reveals that those trichomes contain neurotransmitters: histamines, acetylcholine, and serotonin. Several acids are also in that mix: formic acid (remember my reference to fire ants?), oxalic and tartaric acids. One or more of these compounds can elicit pain or itching. But the cocktail of all those compounds may be the synergy to induce long-lasting pain, itching and inflammation. 

Over the next week, my hand and wrist swelled so much I had trouble moving my fingers and closing my hand into a fist. I had to switch my watch to the right wrist. I usually held my lower arm up, bent from the elbow. If I didn’t, the wrist and hand throbbed in addition to burning and itching. Twice-daily applications of a dermal corticosteroid somewhat alleviated the symptoms, but not enough. Ice also helped, but I couldn’t keep ice on it 24/7. A phone call to urgent care recommended trying an oral anti-histamine and applying a dermal anti-histamine, with icing once every hour if possible. I added a dose of ibuprofen twice a day. The pain subsided before the itching, which was the hardest symptom to  to ignore. 

Why trichomes?

With that anecdote in mind, you may guess the function of some trichomes and why many plants evolved these dermal structures. Not all trichomes are bad, however, Some are merely hair-like, with pigmentation, and cover the leaves. They are inert; no compounds are inside their trichomes. Their functions may be to trap rain and morning dew to cool the surface of the leaves and stems, or to reflect light away from the surface. Many plants in arid climates have these types of trichomes. 

If you do a Google search on ‘trichome’, the most prevalent result is photos of marijuana trichomes. Trichomes on the stems and leaves of hemp plants, including marijuana, are highly evolved deterrents against herbivory by animals. The three different types of trichomes of Cannabis sativa, or marijuana, are “the very factories that produce the hundreds of known cannabinoids, terpenes, and flavonoids” that the plant is known for. Some trichomes -those that look like tall-stalked, bulbous mushrooms- have higher concentrations of the above compounds and cover specific tissues on the plants: the calyx of the flower buds. When crushed, they exude a sticky, odiferous resin that often repulses animals from eating them, except for humans. 

Why did Mesozoic pterosaurs have pycnofibers? Were their pycnofibers the animal version of plant trichomes? Possibly.  A question is, which evolved first? 


12 Mar

Its aroma is almost an aphrodisiac.

It is the timeless scent of an ancient organism
that evolved with the sand and deserts

of the Great Basin.

Many of the Artemesia spp. are very aromatic; their leaves lush with terpenoids. These aromatic lipids are volatile and will relinquish their scents when leaf cells are crushed, or even under the right weather conditions.

Adding to the symphony of volatile compounds are the three isoprene rings that build the  sesquiterpenoids; lactones that repel herbivory, invite the sagebrush checkerspot butterfly to lay their eggs, and gall midges to build galls to house their nymphs.

But they also attract humans that cherish the yin and yang of their leaves and scent. The silver hairs, the trichomes, on the leaf surfaces that catch the sun and dew; the aroma they impart when crushed between fingers, the scent when scattered upon a fire.

In a harsh land where sun and sand cover the earth,

in the shadow of the mountains,

sagebrush provides shade for sage grouse,
structure for fly nymphs,
caterpillar homes,
and an aroma that
between the fingers
of the Ancient Ones.
all Artemesias,
are my spiritual plants.


Sagebrush Galls: Medusa!

16 May

“How galling!! The audacity of this insect making a home in me!”

True; no matter how one organism looks at it, it’s annoying. The word ‘gall’ originates from Middle English (~ 900 A.D) and refers to bile, the bitter fluid from the gall bladder. The figurative word ‘galling’ refers to irritating, offensive, audacity and very annoying behavior.  But how did an abnormal plant growth acquire the same name, gall?

We may never know.

As a child roaming the woods and wild fields, I would often collect tree and shrub leaves and twigs that had protruding bumps in a variety of shapes.  I wondered what these odd shapes were, but it never occurred to me that they might be injurious to the plant, or even malicious at all. Nor did I know then how they were formed.

One day while wandering in the field I found a particularly large growth on the stem of a shrub. Pulling out my magic little ‘looking glass’ (pocket magnifier), I watched half a dozen little translucent bugs crawl out of the ball-shaped growth. In a short time, these bugs acquired color and their wings unfolded away from their bodies. I wondered if the abnormal-looking ball of green was a home for these bugs, and only much later did I learn they were called ‘galls’. And from then on, anytime a person uses the word ‘gall’ or ‘galling’, all I can think of are these appropriated plant cells that serve as a home for small insects.

Five decades later and I’m still fascinated by galls!

Here in the high desert of the Great Basin, galls are common on sagebrush, the most dominant plant. What surprises me is the morphological variety of these galls: the colors, shapes and sizes. So, like the child I was (and probably still am), I have been collecting samples to take back with me, as well as photographing them.

What are galls, anyway?

Galls are an abnormal plant growth induced by various parasitic organisms (1), usually insects. These latter galls will be the focus of a series of posts here as I find examples.

Galls serve as ‘incubators’ for developing insects where they gain nutrition and protection from environmental conditions and predators. Some galls are colorful and easily distinguished from the other plant material. Some are wooly, some round and colorful like tiny plums, some are lobed, and others have spiky protuberances.

Gall-inducing insects are usually species-specific and sometimes tissue-specific on the plants they parasitize. Galls can be found on leaves, stems, shoots, flowers and roots. Combined with gall morphology, these traits will often help to identify which insect is associated with them. However, identifying the insects inside will be the confirmation.

These insects manipulate and exploit the chemistry and physiology of plant tissue to their own benefit and development. Accordingly, galls act as physiological sinks for mobilized plant resources, mostly as nutrition for larvae. Fungi sometimes grow on the interior of the gall surface on which the larvae feed.

Like little houses, galls physically serve as protection from the sun, wind, rain and snow. In fact, because the gall-forming insects control gall formation so well, galls are commonly referred to as their extended phenotype. However, several predatory insects have also adapted to this system by inserting their own larvae inside galls. Then a battle for who eats whom ensues until maturation of one or both species. It’s not uncommon to have more than one species of insect emerge from a gall, but only one of those species induces galls.

Protection is one explanation for the high levels of compounds, such as phenolics and tanins, found in many galls. This is considered a defensive gall trait, protecting the gall against natural enemies outside. Thus, in addition to serving as a nutrition sink and physical protection, some galls have a natural chemical defense.

Sagebrush gall midges

Like any plant, it’s an insect-eat-leaf world out there for sagebrush. Of the 237 species of insects that are associates of sagebrush, 42 are gall-forming insects. Of those, the most predominant are Cecidomiidae, or gall midges. They are a small family of tiny flies that are associated with gall induction.

The most abundant gall midges found on sagebrush are of the Rhopalomyia genus. Although there are 32 species, not all may be present in the same location and area. A recent study suggests that land use or local abiotic conditions may greatly influence the diversity of gall midges.

The adult midges lay eggs in the sagebrush stem tissue. The eggs hatch and the larva secrete saliva into the plant. Compounds in the saliva alter the growth of the injured plant cells and the tissue produces a swelling, or gall, around the young insects. However, the size, shape and color of the developing gall are typically specific to the gall midge species. On the other hand, one species unusually induces a wide range of gall morphologies.

Medusa Galls

During a recent camping trip on Steens Mountain in SE Oregon (and bordering the Refuge), I found many specimens of Medusa galls (Rhopalomyia medusa) on Big Sagebrush (Artemesia tridentate). As seen in the photograph, these galls are composed of numerous leaf-like structures. Looking at the long miniature leafy structures, it’s easy to see how this gall was called “Medusa”.

Medusa Gall on Big sagebrush

The galls develop in October and rest during the winter. They reach full size in the following spring and adult midge flies emerge in April or May. When I was there, May 9-11, the galls were intact with no sign of emergent flies. Considering the elevation (7,300 feet) where I was hiking, patches of snow were common and the climate was barely spring-like.

Authors of a study (2) sampled arthropod diversity on sagebrush in two ecosystems, one surrounded by dryland agriculture and the other area protected from agriculture and significant human use. Their data suggests that diversity of gall midges is highly variable with the dynamics of arthropod-sagebrush interactions and the sagebrush ecosystem. Interestingly, R. medusa was one of a few species that served as an indicator species in low human impact sagebrush habitats. A good description of where I found the many specimens on Steens Mnt.

So, do these galls negatively affect the sagebrush? We will examine that question in a later post!

1. Some bacteria species can also cause galls. This was my first introduction to galls in undergraduate university. Crown gall (Rhizobium radiobacter, formerly known as Agrobacterium tumefaciens) is the textbook and lab example used in plant pathology and lab classes. It is also a common tool to teach Koch’s Postulates. Soil bacterium inserts a small segment of DNA (T-DNA) from a plasmid and into the plant cell. This DNA encodes for genes that produce a plant hormone, auxin (indole-3-acetic acid), via a special pathway that is not used in most plants. Thus the plant has no molecular means of regulating the production of the exocrine hormone. The T-DNA also signals extra production of a group of plant hormones called cytokines, which are involved in cell division. These hormones are responsible for the tumor-like growth of plant tissue and form the galls.

2. Sanford, M.P., Huntly, N.J. 2010. Seasonal patterns of arthropod diversity and abundance on Big sagebrush, Artemisia tridentata.  Western North American Naturalist, 70(1): 67-76.

The Belle of Spring – Yellow Bells

5 Apr

Coming recently from south-central New Mexico I was thrust backwards in the progression of seasons. At the Bosque del Apache NWR daily temperatures were already in the low 80’s and nights above freezing. Here in in the high desert of SE Oregon (same altitude of 4500 feet) spring is still trying to assert her dominance.

Although I arrived at the Refuge during a sunny warm day in bare feet wearing sandals, that was a tease. Night temperatures have been consistently below 32 F (one night at 17 degrees!) and I’m lucky to see day temps in the high 50’s. I wish I had brought more warm clothing.

Two days this week were devoted to hiking and scouting the Stinking Lake Natural Research Area, a ‘wilderness’ area on the Malheur National Wildlife Refuge. Armed with binocular, maps, GPS, water bottle, and thick warm layers, a total of 15 miles were hiked and explored, with the last day accumulating 8.5 of those miles. My back and feet are still protesting (need better boots).

Yellow bells (Fritillaria pudica)

An example of a small spring-fed alkaline lake, the predominant plant community along the shore is alkali-saltgrass/black greasewood. On my way to nearby Derrick Lake I happened to find the first flower of spring here in SE Oregon’s high desert. Diminutive, dainty, bright, and elegant yellow bells are the harbinger of spring in sagebrush country.

Yellow bells can be found in loose dry soil in alpine and sub-alpine communities as well as in sage-steppe lands. It is one of the earliest spring flowers, sometimes appearing in small bare islands surrounded by shallow snow. It needs the early season’s moisture, but can also be found along rocky ridges in the mountains.

Like most other lilies, yellow bells have grass-like leaves which arrive from underground bulbs. The 1-2 nodding flowers branch from the top of a thick round stem. Numerous smaller bulblets grow on the main bulb’s primary roots and the bottom exterior surface, which is why this plant is sometimes referred to as ‘rice root’. Native Americans used the bulb and bulblets as a source of food, cooked or raw.

The bright yellow nodding flowers are short-lived and become orangish or reddish as they age. Dried capsules resemble a dice box, a cylindrical box used to shake dice by the Romans. This is reflected in the generic name for this plant, Fritilaria, derived from the Latin term, fritill, meaning ‘dice box’.

The species name, pudica, is Latin for ashamed or bashful and refers to its nodding habit. On the other hand, there are several more nodding Fritillarias that can be found on the North American continent. Another species I am familiar with is F. affinis, also known as chocolate lily, checker lily, or leopard lily. This flashy nodding flower is often found in the deep woods of western Oregon, again appearing in early spring. This species is not commonly found within the high desert area, instead preferring a more wet, darker and more humus environment. Although this flower’s velvety dark chocolate or purple background is beautifully speckled with orange and yellow, its aroma is repugnant.

How better to attract flies for pollination in a dark moist place than smell like decaying meat?

A wandering verbena (Desert Verbena)

19 Apr
Glandularia bipinnatifida. Photo courtesy of Pam Gordon.

Glandularia bipinnatifida. Photo courtesy of Pam Gordon.

Folks driving along the desert roads this month may see many small tight masses of purple flowers waving in the breeze. The Desert verbena are at their peak of flowering right now.

Here’s another example of ‘mixed identity’. There are many common names for this plant: Desert verbena, Prairie verbena, Dakota vervain, Davis Mountain mock vervain, and Moradilla. While many common names exist for a particular plant, one can usually rely on a more specific scientific name. Not the case here (again).

Older published widlflower guides list this plant as Verbena wrightii, and a member of the Verbenaceae (or Vervain) family. While our plant of the week is indeed in the Vervain family it’s genus and species names have changed.

Glandularia bipinnatifida close up.

Glandularia bipinnatifida close up.

Back in the early 1800’s, naturalist Asa Gray named the plant for Charles Wright , a teacher, surveyor, and plant collector, known notably with the Mexican Boundary Survey. However, new molecular research tools in the last decade or so have determined that a few members of the Vervain family have different chromosomes (numbers and sequences) in their chloroplasts, the organelles in plants that are the powerhouse for producing energy (photosynthesis).

Scientists discovered that some genetic information has been transferred between members of the Vervain and Glandularia genus. In other words, members of these two genus and species have hybridized not just once, but possibly three times as these plants spread north from South America.

Although several plants were once classified as Verbena, and still resemble many of that genus, they have been reclassified (1979) based on genetic similarities and differences. The most commonly known reclassified member is that which was known as Verbena wrightii, or Desert Verbena. It is now recognized in the botanical literature and more recent wildlfower guides as Glandularia bipinnatifida. Although there are two subspecies of this plant referenced (G. bipinnatifida var. cilia. and G. bipinnatifida var. bipinnatifida), their taxonomic classifications remain invalidated and both will find them used synonymously for this species. Perhaps more chemical and molecular studies will elucidate any differences that may exist.

Meanwhile, if you get close enough and smell these plants you may or may not be enamored of their fragrance. While many members of the Vervain family and Verbena genus have pleasant scents, this one had to sit outside after I gathered some samples yesterday. 🙂

For those interested in a recent review of the latter issue, see the following reference, “Taxonomy of the GLANDULARIA BIPINNATIFIDA group (Verbemaceae) in the USA”, by Guy Nesum (of Forth Worth!) in Phytoneuron, issue 46, 2010.

Springing forwards and backwards

25 Mar

Most deserts are known for their extreme weather, especially temperatures. The northern Chihuahuan desert is no exception. We have had an unusually cold winter with prolonged periods of below-average temperatures. Of course, that parallels the rest of the country as well. However, here we have had temperatures in the 90’s during the day and in the high 30’s at night. Spring usually arrives with a pattern of more consistent temperatures and less extremes. This year, spring continues the vacillating extremes of temperatures. In many cases, new growth on plants have been damaged by repeated bouts of frost after days with high temperatures (high 80’s to near 100 degrees).

Regardless, many flowers are popping and leaves are emerging on trees, shrubs, perennials and even cacti. The yuccas have been sending up their giant flower masses throughout the southern Big Bend area for a few weeks now, and the coveted bluebells carpet many roadside areas. I have been capturing some of the lesser known flowers the last week or so, which also provides me with an opportunity to practice macro-photography. I will post some of those photographs here.

Feather Dalea (Dalea formosa)


Bowl Flax (Linum berlandieri)




Velvety Nerisyrenia or Mesa Greggi (Nerisyrenia camporum)

An Oasis in the Desert

11 Mar

I and a visitor recently enjoyed a hike to one of my favorite places in this area of Big Bend: Cattail Falls. A relatively hidden gem in the Big Bend National Park, Cattail falls is a waterfall and stream, which supplies water to the park’s infrastructure. The canyon is also a delicate microenvironment and susceptible to damage from human impact. For these reasons, the hike and the destination is not on any of the park maps. On the other hand, it’s not a secret, either.

A rough road accesses a parking lot for the trail head that branches off to many trails. One trail goes to Oak Spring, which then extends into a long and arduous hike up the side of the western Chisos range and eventually reaches the pour-off affectionately known as the Window.  The other trail heads up towards the southeast to the canyon containing the pour-off and stream of Cattail Falls.

Oak Springs

The area first noted has natural and historical significance. At the Oak Springs and Creek one can see the old and large live oak that is bent and parallels the ground. This immediate area was also once the home site of Homer Wilson and his family. Their ranch, Blue Creek Ranch, was one of the largest in the Big Bend region from 1929-1944. The house (a Sears and Roebuck structure that was ordered by mail, shipped by rail to Marathon, then brought in by ox and mule carts to here) was here at Oak Springs. The Park protocol at that time was to bulldoze anything that was considered ‘human footprint’ to return the landscape to its ‘wild’ state. Which was naive on their part, and they now regret in hindsight.

The house was a bit further up the bank to the right of that tree. If one digs around enough in the thorny scrub brush, you can see remnants of the old rock retaining wall that was in front of the house, and remains of Mrs. Wilson’s terraced vegetable and flower gardens. Gone are the prolific fruit and nut trees, and even the old spring is now diverted into big green tanks and piped away from the creek that flowed and provided an oasis for wildlife and humans alike.

The ranch’s large rock structure that served as the ranch working headquarters and seasonal home remains in Blue Creek. A trail to this structure, now a historic land mark, can be accessed from Maxwell Scenic Drive in the Park. For those interested in early ranch life in Big Bend, and in many of the historical ranches in the National Park (Wilson’s ranch, Sam Nail ranch, etc), I recommend reading the book Beneath the Window: Early Ranch Life in the Big Bend Country  by Patricia Wilson Clothier, Homer Wilson’s daughter.

Cattail Canyon and Falls.

Cattail Canyon Creek

Many canyons lay hidden within the sky island that is the Chisos Mountains. Streaking the slopes in and out of the Basin, these canyons vary from narrow winding slots to wide gulleys with towering cliffs. Because most of the steep canyons are inaccessible, except for experienced canyoneers, some of these canyons may have had barely a dozen human footprints in all their history. Others are visited more frequently because of developed and primitive trails traversing them, such as those on the Window Trail in the Basin.

One canyon scraped into the western slope of the Chisos group is Cattail Canyon. Only those people with experience in canyon climbing and with rock climbing gear can traverse most of the canyon, for it winds along and down with slots and loose screed. As with most canyons, water is an integral part of its formation and continued geological change. The entire length is dotted with pour-offs, water falls and tinajas.

Some sources, including an older topo map, claim that water runs year-round down this canyon. But, of course, that claim can’t be static or accepted without consideration of the local climatic conditions. After all, historical records testify that 50 years ago the Rio del Norte and Terlingua Creek had running water (and plenty of fish) year round. But, despite our own mortal timelines, the climate is changing and the aridity of the Chihuahuan Desert increases and expands its boundaries northward.

Referring to a topo map, you will find Cattail Canyon between Ward Mnt and the ridge west of Oak Canyon, almost N-S along the western slope of the Chisos Mnts. The canyon runs about 5-6K feet in elevation and ends with a pour-off at the northern-most bend west at ~4,200 feet.

This pour-off, the only portion of Cattail Canyon that is easily accessible, is Cattail Falls (despite that many waterfalls are part and parcel of this canyon). However, you won’t find the trail on any maps and in any guides, except on an old topo map. Because the waterfalls and tinajas are fragile ecosystems, the park attempts to reduce human traffic and consequent environmental damage often associated with heavy use. Their methods for reducing human visitation to sensitive areas are by physically prohibiting access or by removing references to these area from guides and maps. However, some signage remains with limited directions for the trail, and the trail is maintained in primitive condition.

The trail from the split off the Oak Canyon/Spring trail climbs a few hundred feet with an easy one-mile walk. Entering the pour-off area is like emerging through a door into a magical wonderland. The trail ends at tossed giant bounders which require scrambling over, carpets of moss and ferns, and small pools of water that trickles over miniature falls. The most magnificent feature is a vertical concave wall of multicolored and striped rock. During our visit, water was trickling down from a V-notch 45′ up and dripping over a black stone surface where small groups of ferns and other plants found foothold to root and bathe in moisture.

Cattail Falls and the pour-off.

A large pool of water lies at the base of this cliff, its edges damp and rich with thick carpets of black organic matter where grasses and ferns grow. This desert oasis is a unique and fragile ecosystem. Here grow abundant trees, ferns, cattails and flowers. Along with this moist environment are a variety of birds and butterflies.

Not only is the organic life attractive, but also the varying shapes, colors and sizes of rocks. From yellow, pink and rosy, to angular and polished smooth, stones small enough to pick up to boulders you could stretch out and nap on.

I was especially delighted to find small areas blanketed with an old companion from the north country (New England and Pacific Northwest): maindenhair ferns. A genus –Adiantum– with at least 200 species, only four or five are indigenous to the North American continent, one of which is found only in the western states. These plants prefer a humus-rich and moist soil, but can be found growing in crevices and small pockets on the surface of rock walls and, especially, near and in waterfalls. They are most plentiful along stream banks.

Although they are typically evergreen, meaning that they do not lose their leaves in winter and can even be found under several feet of snow, they thrive best in areas sheltered from harsh winds and hot sun. Despite that one would not expect to find ferns growing in a desert environment, remember that that the falls and canyons are part of a sky island; a gignatic land formation jutting up out of the desert floor over a thousand feet, where a variety of ecosystems overlap. Sky islands are oases unto themselves, even creating their own weather because of the geographic interruptions in the lower atmosphere.

This is the magic of these sky islands, and the uniqueness of their associated biology: the juxtapositions of plant and animal life that live here. Thus, I was delighted to find an old friend in a tiny pocket of wonderland. And enjoying the magic world so different than half a mile away.

Someday I will spend an entire day. Watching life unfold and change in this little pocket of a sky island oasis.

(click on images to see larger files)

Maidenhair Fern.

Cedar Lobelia

Agave hidden in branches and vines.

Reflections in pool at the base of the cliff.

View of the desert below and NW of the Chisos Mountains.




Fendler’s Bladderpod

4 Mar

One of the first wildflowers to pop up like little yellow stars in southwest Texas is Fendler’s Bladderpod (Physaria fendleri). Starting last week, these tufts of small yellow flowers are marking many of the desert areas like globs of bright jewels.

Here again was an adventure in identification for several reasons. And I will outline how I pursued identifying this plant. Most of the yellow flowers we see with non-fused petals belong to the very large family Asteraceae, or the sunflowers, and have multiple flower petals (more than 4 petals/flower). However, a few yellow flowers have only four or less non-fused petals. Those usually belong to a different family of plants: the Brassicaceae, or mustard family.

Fendler’s Bladderpod

Once the flowers were narrowed down to the family, then one must use details of leaves, seed, and growth habit to correctly identify the plants. This process is called ‘plant systematics’, most commonly referred to in plant guides as ‘keying’ a plant based on their parts. But that also has limitations, as I will explain in a bit.

When the flowers were keyed in the mustard family and in a genus (Lesquerella), sometimes collectively called ‘bladderpods’, the next step was to determine which species this plant was. This was more difficult because the flowers and leaf shape are typical of two species: Gordon’s Bladderpod (L. gordonii )and Fendler’s Bladderpod (L. fendleri). They both have tiny silver hairs on their leaves and stems. And they grow in the same region!

The only differences between these two species are that the Gordon’s Bladderpod is an annual, whereas the Fendler’s Bladderpod is a perennial. Because of that, the Gordon usually begins flowering a month or two later than the Fendler’s. Additionally, the Gordon’s usually have longer stems that may lie on the ground and turn up at the tips, and thus they have a more open appearance. The Fendler’s, on the other hand, often grows in more compact and upright clusters.

The other issue with identification of these plants is in the names. Again, I ran into reclassification of an entire genus of plants where the literature, especially plant guides, is very slow to catch up. Including many online plant databases (even state and federal).

The first specimen of this plant was collected in 1847 from near Santa Fe, NM, by Prussian-born natural historian Augustus Fendler. From the specimen, the plant was named and characterized by the famous botanist Asa Gray as Vesicaria fendleri.  Years later (1888) the curator of the Gray Herbarium (of Harvard University), Sereno Watson, who was appointed by Gray, renamed the plant Lesquerella fendleri.

Now, move ahead in time to 2002 when a team of botanists and biologists petitioned the organizations involved in taxonomical name conventions to move all the plants of the genus Lesquerella to another existing genus, Physaria. Why would they propose that change? Traditionally plants have been categorized and named based on comparative data: morphological, ecological and distribution. However, in the past two decades the addition of more sensitive and technical tools, such as molecular biology and genetics, have been applied to confirm similarities and separate differences. Consequently, some organisms are now determined too similar rather than more different and are reclassified together in the same genus, even species. Conversely, some molecular differences are important enough to separate some species that were once classified together.

When in doubt, I have always turned to a database used by nearly all biology, molecular and genetic scientists, and which is continually updated, sometimes more than daily. It is crucial for all scientists to keep up with changes in scientific data and reporting, which truly reflects the dynamic world of life sciences and discovery. Although many of the media and even federal plant databases still use the old naming convention, the genus Lesquerella  is no longer accepted or correct.  As of now most of the species within that genus are now included in the official genus name, Physaria. Unfortunately, it may take another five or more years for that name to propagate through all the databases and into the literature, including the nature guides everyone uses for identifying plants.

An ending note about these two bladderpods: they can be poisonous to livestock, especially horses. The seeds especially contain a large amount of oil that can be toxic if eaten in excess. On the other hand, the Fendler’s Bladderpod is now being considered as a commercial source of oil to make plastics, grease and as an ingredient in cosmetics, mostly to replace castor oil. Me, I just like enjoying their little yellow mounds of stars on the desert floor.

Fendler’s Bladderpod

Texas Persimmon

17 Feb

Texas Persimmon (Diospyros texans)

214_2585-2A common wild shrub in the Texas hill country and Trans-Pecos area, it is also known as Mexican Persimmon and Black Persimmon. Shrubs can grow up to 25 feet high with attractive curving branches. An easily identifiable trait is the smooth gray bark that sometimes peels off in sheets on older wood, revealing pinkish and beige wood underneath. The leathery dark green leaves can be evergreen (persistent) depending on local climate. I saw shrubs in Lajitas in full leaf early February, but nearly all leaves had fallen off shrubs at the Terlingua Ranch Lodge area.

Small white flowers appear February-June, with male and female flowers on different plants. Accordingly, fruits form on only female plants. Small (1” diameter) seeded and juicy black berries ripen in mid-summer. The berries are eaten by many bird species and mammals, including turkey, coyote, javelina, raccoon. White-tailed deer eats leaves and fruit. The dense branches are also favored by birds for building nests, as indicated by a shrub growing close to where I am now.

When ripe, the fruits are edible with a sweet and sour taste. Black juice stains fingers and fibers. Fruits were used as an astringent for treating sores in the throat and mouth, and the bark was chewed to treat heartburn. Also, local accounts praise persimmon jelly and wine.

The Texas persimmon is a favored landscape tree with aesthetic qualities accompanying its wildlife and food attributes. Young trees are slow growing and like partial shade with abundant water. Conversely, established plants tolerate full sun and limited water. Dried fresh seeds may germinate, but the plant is difficult to propagate by cuttings. This shrub is a perfect candidate for xeriscaping in semi-arid and arid environments and makes its home quite well here in the Big Bend region.



5 Feb

Evergreen tri-lobed leaves of Agarita.

Algerita (also, Agarita). Mahonia trifoliolata.

This small to medium sized evergreen shrub is of the Barberry (holly) family. It is drought and heat tolerant, often found nestled under taller shrubs and trees in arroyos and in desert scrub chaparral. The stiff silvery-green and tri-lobed leaves have spiny tips, and the tiny but aromatic yellow flowers grow in clusters.

Stands of agarita provide good cover and shelter for quail and other small mammals. dThe small red berries produced in mid to late spring are favorite food for birds, deer and small mammals. The fruits contain a slightly sweet and sour juice, good for making jams, jellies, and even pies. When pressed and sieved,  juice from the berries can also be used to produce an adgarita wine, or it makes a sweet tart refreshing drink.

Every part of the plant has been used for medicinal purposes, food and dyes. Berberine,  present in rhizomes of most Mahonia species, has antibacterial effects and is used as a bitter tonic. Since it is not appreciably absorbed by the body, it is used orally in the treatment of various enteric infections, especially bacterial dysentery. Root extracts were used to dye buckskins and basketry yellow. Interestingly, the roots provided a yellow dye that was used as one hue of color-coded parachutes during World War II.

Seedlings grow readily from seed, and this shrub makes an attractive addition to xeriscaped gardens. Agarita is suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil.  It also prefers full sunlight, but can often be found mingled in the understory of other taller shrubs.

Mahonia trifoliata (agarita)


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