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Botany Photo of the Day
In science, beauty. In beauty, science. Daily.

Dec 18, 2014: Arnica latifolia

Arnica latifolia

This photograph is from several summers ago. I hope I've identified the plant correctly. Arnica latifolia is commonly known as mountain arnica or broadleaf arnica. It is widely distributed in western North America from Alaska to northern California and east as far as Wyoming and Colorado. As one common name implies, it is generally a species of mid- to high-elevations. Habitats where it can be found vary, ranging from forests to rocky slopes to meadows.

Identification of Arnica latifolia can be problematic, as plants can be similar in appearance to Arnica cordifolia. The latter species, though, has pubescent leaves and achenes, larger capitula (flower heads) and a tendency to grow as single plants. Complicating the matter of identification even more is that the two species hybridize, and, to quote the Illustrated Flora of British Columbia, "numerous intermediates may be encountered".

Digging a little deeper thanks to the late Dr. Gerald Straley's 1980 Ph.D. thesis, Systematics of Arnica, Straley asserts that Arnica latifolia likely evolved from Arnica cordifolia, and, "The close relationship of these two species can be seen in numerous populations which combine many of the morphological characters of both species". In turn, Straley also notes that Arnica latifolia is likely the progenitor species of the serpentine endemic Arnica cernua and perhaps a hybrid parent of the subalpine-alpine Arnica gracilis.

Something else I will have to keep in mind for future identifications in the field thanks to Dr. Straley is that Arnica cordifolia has leaves that are distinctly fragrant when bruised, compared with little to no fragrance in Arnica latifolia (now I have to wait until next summer to try this...).

Dec 17, 2014: Mimosa pudica

Another entry written by Tamara Bonnemaison, who scribes:

Thank you to Lão Hac (aka thtungdl@Flickr) for posting this photograph of the fascinating Mimosa pudica (original image | other images of Mimosa pudica by Lão).

Mimosa pudica, or sensitive plant, folds up its leaflets in response to touch or movement. This species was featured by Taisha in-depth earlier this year (February) as part of a series about the nastic movements of plants. Taisha's entry on Mimosa pudica provides great background information on the sensitive plant while also describing the mechanics of nastic movements.

The reason I am revisiting this species so soon after Taisha's entry is because of a publication made after that posting. In May, Dr. Monica Gagliano et al. published the results of a study demonstrating that Mimosa pudica is able to learn and "remember". In Experience Teaches Plants to Learn Faster and Forget Slower in Environments Where it Matters, (Oecologia, 175(1):63-72), Dr. Gagliano (an animal ecologist) and her research team used methods typical to the study of animal behaviour to understand how Mimosa pudica acquired learned behaviour.

Key to this study was the sensitive plant's ability to fold its leaves when touched, dropped, or shaken. The researchers used a controlled drop system to prompt the touch response. After being dropped multiple times, it was observed that the Mimosa leaves would stop folding when disturbed in this way. In other words, the plants became habituated to being dropped. Intriguingly, plants that were in low-light conditions more quickly learned to remain open upon being dropped compared to plants that were not stressed for light. This learned behaviour was retained over a period of four weeks, even if the low-light plants were subsequently exposed to higher light levels.

The research of Dr. Gagliano and her team is part of a developing field of science dubbed "plant neurobiology" (though plants do not have a nervous system), where the process of science is being applied to how plants learn from and respond to their environment. Michael Pollan covered the topic of plant intelligence in a December 2013 article in the New Yorker: The Intelligent Plant: Scientists debate a new way of understanding flora.

Dec 12, 2014: Dictyonema huaorani

Dictyonema huaorani

BPotD work-learn student Cora den Hartigh is the author of today's entry. She writes:

Dictyonema huaorani is a lichen I have been researching quite a lot this semester. For a directed studies project, I chose to investigate hallucinogenic lichens--a hybrid between popular lichenology and scientific enquiry. It was a lot more difficult than anticipated, but I finally turned in a short book, over a week late! That's just how it goes sometimes. Nevertheless, I contacted Michaela Schmull at the Harvard Herbarium, who was able to forward me this magnificent scan. Now I can share the story here!

This is a scan of the thallus, or vegetative structure, of Dictyonema huaorani. This specimen was collected in 1981 by Wade Davis and Jim Yost, two explorers in eastern Amazonian Ecuador conducting ethnobotanical research with the Waorani people. Yost had heard rumours of this lichen for seven years before finally locating this individual. To date, this is still the only known specimen in existence. As you can see by the label, this lichen was found growing on rotting wood near the confluence of the Quiwado and Tiwaneo rivers in Napo state. Known as nɇnɇndapɇ by the Waorani, the lichen has been used by "bad" shamans to curse others and also been noted to cause severe headaches. It was reputed to potentially have hallucinogenic properties.

The unidentified specimen was forwarded to Dr. Mason Hale, who suggested that it might be a species of Dictyonema, perhaps similar to Dictyonema sericeum. A conclusive identification would not be made for another forty years--this past November! A team of scientists sampled the specimen's DNA and found it to be an as-yet unrecognized species, which they named Dictyonema huaorani. Even more fascinating, they were able tentatively ascertain the presence of psychoactive compounds: tryptamines and psilocybin. Psilocybin is notably found in the infamous Psilocybe cubensis (though also in least 200 other species of fungi), but this is one of the first publications indicating psychoactive compounds in lichens!

Although no fresh material is available, the dried specimen hints at how stunning and ethereal this lichen might look. You can also get a good idea by taking a peek at some similar species, of which there are many! Just recently, a molecular study of Dictyonema glabratum revealed the taxon could be split into at least 126 different species. They make for a lovely colour palette!

Lichens are the result of a sort of pact struck between a fungus and something that can photosynthesize, usually an alga. Because the fungus (or mycobiont) cannot produce its own food, it relies on its photobiont partner for sugars. Algae, on the other hand, have a hard time taking up water and staying hydrated. A lichen forms when a compatible alga and fungus team up (see illustrations). The fungus will form a thick protective layer of hyphae called the cortex. Beneath the cortex is a layer of algal cells, photosynthesizing away, suspended above a loose mesh of more hyphae called the medulla. In some lichens, particularly foliose or fruticose ones, a lower protective cortex is formed below the medulla. This is not always the case, though. There are the jelly lichens, which are a jumble of photobiont and mycobiont without any sort of stratification, or lichens with photobiont packed together in cephalodia. Crustose lichens never have a lower cortex: instead, they fuse directly to their substrate. Some lichens are even able to re-assemble themselves in a few months if turned upside-down, moving all of the algae through the medullary layer to face the opposite cortex where they will be exposed to more light.

The lichen complex has been observed primarily among fungi in the Ascomycota, but about 1% of lichens have a basidiomycete as the mycobiont. The photobiont, too, can be a cyanobacterium instead of an algae. This occurs in roughly 10% of all lichens. Dictyonema is particularly bizarre because it is a basidiolichen teamed up with a species of Scytonema, a cyanobacterium!

You can read more about lichens via Lichens of North America or the delightful Ways of Enlichenment.

Dec 10, 2014: Etlingera corneri

Etlingera corneri

BPotD work-learn student Tamara Bonnemaison authors today entry:

Thank you to 3Point141@Flickr for this excellent photo of Etlingera corneri taken at the Fairchild Tropical Botanical Garden in Florida, U.S.A. This image is one of a series of impressive ginger photos taken by 3Point141@Flickr; visit the ginger album to view the rest.

Etlingera corneri, also known as ka lo or rose of Siam, is a member of the ginger family that is native to southern Thailand and the northern region of the Malay Peninsula. There are about 70 members in Etlingera, and Etlingera corneri was only described in 2000 after John Mood and Halijah Ibrahim found that Etlingera venusta had been used to refer to two different species. The naming of rose of Siam has not been without controversy; C.K. Lim was studying this species at the same time as Mood and Ibrahim submitted their article to the Nordic Journal of Botany. Lim rapidly established a new journal and fast-tracked a publication in the attempt to be the first to describe what he called Etlingera terengganuensis. A subsequent article in the Nordic Journal of Botany, written by Kai Larsen (2000) defended Etlingera corneri as the correct name, which is the name that I have chosen to honour in this article.

Another Etlingera, the popular torch ginger or Etlingera elatior, was featured on Botany Photo of the Day in 2007. Torch ginger is cultivated in tropical climates as a garden ornamental, for use in flower arrangements, and as a food plant. Although not well known, rose of Siam is also a good candidate for many of the same uses. This species is said to produce more blooms than the other taxa of Etlingera, and the glossy red flowers are large, showy, and long-lasting. Like all members of the Zingiberaceae, rose of Siam has cells that contain essential oils, rendering the inner sheathes of the shoots tasty on their own or as a flavourful condiment.

After seeing the photo that accompanies this write-up, I was surprised to learn that rose of Siam is a perennial herb that grows to 3 or 4 meters. The photo shows the shorter, leafless stems that bear the inflorescence, and just barely shows the leaf-bearing stems which are found growing high above. The showy parts of the inflorescence are composed of two rows of sterile bracts that are rounded or truncate (Etlingera venusta has bracts that are tapered to a point) and that persist past infructescence, a quality that makes rose of Siam potentially even more desirable as a cut flower than torch ginger, whose bracts decay more quickly.

Dec 6, 2014: Saxifraga paniculata

Saxifraga paniculata

A photograph and written entry by Tamara Bonnemaison today. She scribes:

During a morning with frost a few weeks ago, the silvery-tipped leaves of this Saxifraga paniculata stood out among the many other beautiful specimens in UBC Botanical Garden's Alpine Garden. Daniel has been patiently teaching me to use the BPotD camera, and despite my best efforts, I was not quite able to capture the glow of the morning sun playing across the surface of the saxifrage's rosettes. This photo comes fairly close; for the rest, you'll need to use your imagination.

Saxifraga paniculata, also known as lime-encrusted saxifrage and white-alpine saxifrage, is a circumboreal species that is found in calcareous boreal, subalpine, and alpine habitats in North America, Europe, Scandinavia, Iceland, and Greenland. This species' common name is a result of lime-secreting pores on the leaf edges, which give the toothed leaves a silvery or 'encrusted' appearance. What I had at first thought to be the work of a particularly hard frost was actually the combination of frost and secreted lime, both of which contributed to making this plant literally glow against the shaded ground.

Encrusted saxifrage is a stoloniferous perennial that is extremely hardy. Its stiff, leathery leaves form 3cm tall rosettes that close as they become desiccated, with the outer leaves acting as an evaporative and solar shield for the younger leaves in the centre of the rosette. During times of extreme drought, these outer leaves dry out completely, but the plant itself is protected and survives. The species is also able to survive a short growing season and long periods of cold-induced photoinhibition (meaning that it is so cold that very little photosynthetic activity can occur). On top of having to survive extreme cold, drought, and insolation, Saxifraga paniculata must contend with an irregular supply of pollinators. However, it can both reproduce vegetatively through its stolons and self-pollinate.

The perfect flowers of lime-encrusted saxifrage are quite beautiful. I came across this species at the wrong time of year to capture the white, five petaled flowers, but thankfully these have been amply photographed by others. The Acta Plantorum website has many photos that show the curious purple-dotted white petals, as well as some images of lime-encrusted saxifrage growing in its alpine habitat.

Dec 5, 2014: Rhytisma punctatum

Another entry from BPotD Work-Learn student Cora den Hartigh today. She writes:

Late autumn is the time locally to observe this common fungus. Richard Droker (aka wanderflechten@Flickr) took these photographs of Rhytisma punctatum a few years ago (image 1 | image 2). This fungus and its relatives are common and widespread wherever maples are found, in Asia, Europe, and North & Central America. Thank you, Richard, for capturing this and for all your stunning microscopic and close-up photography!

An asocmycete, Rhytisma punctatum is known as the speckled tar spot fungus. It is characterized by black freckles on fallen maple leaves. Called "stromata", the little black speckles are actually tough pods of tightly-woven mycelium meant to protect reproductive structures. The mycelium is made up of a web of hyphae, which look like tightly woven threads composed of chitin (the same substance found in insect exoskeletons and butterfly wing scales). Fruiting mushrooms are also woven from hyphae, but are more 'soft' than these little black pods because the hyphae threads are woven less tightly, like a crochet scarf rather than thick work gloves.

These stromata in the images are not mature yet, though! Dormant, they will overwinter on fallen leaves until the spring. Then, as the new maple leaves unfold and in the presence of ample moisture, Rhytisma punctatum will torpedo filamentous ascospores into the air hoping to colonize new growth. Though the force at which they torpedo these ascospores might only carry them about a millimetre, agents such as windy drafts, critters or water might aid them along. Tom Volk at the University of Wisconsin has posted some fabulous pictures of these ascospores.

With its stromata, Rhytisma punctatum resembles freckled pointillism (e.g., some of the work of Seurat). A very similar fungus, Rhytisma acerinum, has larger conglomerated blotches, or "stroma", that exhibit more closely to impressionism (e.g., see Monet or van Gogh).

Usually this fungus is not considered to cause significant damage to the tree. It is often only observable when the black speckles develop in the fall. However, the fungus does cause nitrogen and phosphorus to be retained in the tissue of the leaves rather than withdrawn into vascular tissues in the autumn, which would certainly impact tree vigour.

What I find particularly intriguing about this photo is how some infected, fallen leaves will maintain chlorophyll-green around the fungus even as the rest of the leaf tissues senesce. Known as "green-islands", these colourful spots indicate active photosynthesis. The fungus may be either producing or stimulating localized plant hormone production, e.g., cytokinins, in order to maintain and farm chloroplasts. It can then continue to feed itself and grow, prolonging its active life cycle beyond that of its host. This phenomenon is also known to occur with some leaf-mining insects and their bacterial endosymbionts (see: Kaiser, W et al. 2010. Plant green-island phenotype induced by leaf-miners is mediated by bacterial symbionts. Proc. Biol. Soc. 277(1692):2311-9. doi: 10.1098/rspb.2010.0214 ). Here's a portion of their article abstract:

"...We show that the phytophagous leaf-mining moth Phyllonorycter blancardella (Lepidoptera) relies on bacterial endosymbionts, most likely Wolbachia, to manipulate the physiology of its host plant resulting in the 'green-island' phenotype--photosynthetically active green patches in otherwise senescent leaves--and to increase its fitness. Curing leaf-miners of their symbiotic partner resulted in the absence of green-island formation on leaves, increased compensatory larval feeding and higher insect mortality. Our results suggest that bacteria impact green-island induction through manipulation of cytokinin levels..."

Dec 4, 2014: Daucus carota

Daucus carota

An entry from BPotD Work-Learn student Cora den Hartigh, who writes:

Today, we have a different sort of image from a Canadian photographer living in Munich, Germany. Anne Hoerter takes her subject apart and slowly reconstructs it with photographs, sometimes using up to 40 or 50 images to achieve a single piece that is alive with motion and depth. The graceful movement Anne was able to embody with this stunning artistic representation of Daucus carota, or wild carrot, took three months to produce. Thank you, Anne! You can see more of Anne's work at her website, Áine - Fine Art Photography.

Daucus carota is a familiar umbelliferous species known by many common names, including wild carrot, bishop's lace, and (in North America) Queen Anne's lace. It is a Eurasian and north African native that is widely naturalized in other temperate areas of the world. In North America, one hypothesis is that its initial spread was due to being carried across the continent by settlers in grain sacks. Described by Linnaeus in 1743 in Species Plantarum, Daucus carota has also been recognized widely in poetry and folklore. William Carlos Williams' personifying poem is one example. Williams refers to a purple 'mole' in the white inflorescence. This 'mole' is actually a single anthocyanin-rich flower coloured deep red or purple at the centre of the umbel. Presumably, this single flower helps attract pollinators, perhaps acting as a nectar guide. Another story explains this red flower as a speck of Queen Anne's "blood" dropped from a needle prick while sewing lace.

The little red flower is a particularly useful diagnostic character given that the plant's feathery leaves, floral structure and tall-standing growth habit are similar to a number of poisonous relatives: poison hemlock (Conium maculatum), water hemlock (Cicuta spp.) and fool's parsley (Aethusa cynapium) are counted among these! Unlike many of its toxic family members, Daucus carota tends to grow in dry open habitats and has solid hairy stems. When young, its roots are edible and smell like fresh carrots. With age the roots grow woody and the floral structure curls inward like a vase. I always look for those hairy stems and think of the ditty "Queen Anne has hairy legs"!

In many jurisdictions where the species has naturalized, Daucus carota is considered to be a noxious weed. Doug Larson's oft-cited quote, "a weed is a plant that has mastered every survival skill except for learning how to grow in rows", comes to mind. Brushing up against the leaves can, in some people, cause skin to be more susceptible to UV damage, but this plant can be exceedingly useful. As a companion crop, it boosts tomato production and cools lettuce; as a dyestuff, it imparts creamy tones. Medicinally, the plant dates back to early Greek and Roman writings for digestive disorders, kidney stones, skin tonics, aphrodisiacs, insecticides ... the list goes on. The seeds are also a tasty flavouring for soups and stews not unlike asafoetida; however, they should be consumed with some caution. A relative of Daucus carota, silphium, is thought to have been harvested to extinction for use as a contraceptive and general tonic in ancient Cyrene (Lybia today). So important was silphium that coins were imprinted with the image of the plant. This paper from Economic Botany provides some fascinating archaeological investigation, while Wikipedia gives a good overview. Experimental trials in rats have suggested that extracts from Daucus carota seeds have "...at a lower dose showed anti-implantational activity [of the fertilized ovum into the uterus], whereas higher doses caused fetus resorption. The main effect of the extract appears to be an abortifacient activity." Perhaps not ideal for dinner party soup stock.

Daucus carota has been featured once before on Botany Photo of the Day.

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