Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel

Thank you to David Tarrant for today's photograph. It was taken in El Charco del Ingenio in San Miguel de Allende, Mexico. Thanks again, David!

The genus Matelea contains approximately one hundred and eighty species distributed in subtropical and tropical areas of the Americas. Collectively, these twining vines are known as the milkvines, a common name similar to their cousins the milkweeds (the genus Asclepias). Matelea pilosa is a relatively unknown species (few search engine results, no common name), but the Neotropical Herbarium Specimen database at the Field Museum does have a scanned specimen online.

Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel

Argemone munita, or prickly poppy, is divided into four subspecies. Assuming I'm correct in my identification to species (which I may not be), it was trivial to identify this to subspecies rotundata – it is the only subspecies which occurs in Nevada, where this photograph was taken.

Read more about prickly poppy via Calflora.net.

This is the second thistle from western North America to be featured on BPotD recently that is endemic to only one mountain or small mountainous area. Cirsium peckii, or Steens Mountain thistle, can only be found on Steens Mountain or the nearby Pueblo Mountains of Oregon. Cirsium clokeyi, on BPotD nearly two months ago, is endemic to the Spring Mountains of Nevada. When a pattern like this becomes noticeable, it is certain to catch the attention of botanists – and it has. Dr. Dean Kelch of the Baldwin Lab at the University of California, Berkeley, has investigated these narrowly-distributed endemics within Cirsium. Despite having low genetic diversity (by measure of rDNA), the Cirsium display an unusual amount of ecological diversity. The conclusions? Cirsium in North America have either undergone a rapid ecological radiation (meaning new species have evolved quickly to fill ecological niches) or the rDNA of thistles is highly conserved across species (meaning that as species of thistles evolve, this particular type of DNA does not change as much as it would typically be expected to do given the patterns in other plant groups). See: Kelch, DG and Baldwin, B. 2003. Phylogeny and ecological radiation of New World thistles (Cirsium, Cardueae - Compositae) based on ITS and ETS rDNA sequence data. Molecular Ecology. 12: 141-151.

Photographs of Cirsium peckii in flower can be seen here and here.

Lyall's mariposa lily only occurs in British Columbia and Washington state. On the Canadian side of the border, it is considered a threatened plant (COSEWIC report on Calochortus lyallii in PDF format), as it can be found in only a few locations within 5km (3 miles) of the Canada-US border. In Washington state, it is relatively more common in the northern and central interior regions, where it occasionally occurs in large, dense populations (distribution map).

A short (to 20cm or 8in) plant of dry, open Douglas-fir and pine forests, it is threatened by cattle grazing and inappropriate reforestation practices post-burn or post-logging (too dense of a canopy will reduce its population numbers significantly). Competition from weedy invaders can also be a problem. The story of cattle grazing and weeds being problematic for native plants is repeated ad infinitum throughout the intermountain area, we observed.

Of the 56 species of Calochortus that occur in North America north of Mexico, we encountered 5 species during our expedition. That number may not seem like a lot, but most of those 56 species are California endemics (where we didn't visit). For those species that do occur outside of California, I think we encountered nearly half of them.

Paging through the wildflower guides, I often find particular wildflowers I'd like to see one day. While I'm not so keen as to actively seek them out (though Lewisia rediviva was one of the exceptions), when I do find them, I'm fairly delighted. Encountering Clarkia pulchella for the first time was a pleasant surprise. Searching among the (omnipresent) cheatgrass for plants that may be in seed, I spotted a patch of purple flowers. The general habit of the plant flagged it in my thoughts as “That's different from what I've seen before”, so an immediate investigation was necessary. Having seen it in books and knowing its unique appearance, an immediate identification was made as soon as I was close enough to see the petals.

Clarkia pulchella has several common names, including clarkia, pinkfairy, deerhorn clarkia and ragged robin. The Discovering Lewis and Clark site provides Lewis's description of the plant as well as Pursh's painting for more information about this western North American native.

Curiously, the pollen of Clarkia pulchella helped make an important contribution to science. The phenomenon called Brownian motion, whereby particles suspended in a fluid move randomly, was first observed by botanist Robert Brown in the vacuoles of Clarkia pulchella pollen grains. Brownian motion was eventually used as evidence of the atomic nature of matter (i.e., that matter was composed of atoms and molecules) by Albert Einstein, Jean Perrin and other physicists. Brian J. Ford discusses the discovery in a 1992 paper published in The Microscope (40 (4): 235-241): Brownian Movement in Clarkia Pollen: A Reprise of the First Observations

Photography resource link: if you enjoy photomicrography, Small World from Nikon is likely already on your list of bookmarks. If not, it should be – it showcases some of the best photomicrographs through an annual competition. Even though this year's winners have been chosen (and will be announced in the autumn), a “rate-this-photo” system is in place to reveal if there is any difference between what the judges have chosen and what the public would choose. Thanks to David Brownstein for the suggestion.

Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel

Thank you to Eric in SF@Flickr for sharing today's image (original via BPotD Flickr Group Pool).

Fringe flower is a relative of witchhazel (in fact, it is sometime given the same common name). The Plants for a Future database reports on the medicinal uses and cultivation of this east Asian species.

Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel

Thank you to Stephen, aka stephenbuchan@Flickr from Edinburgh, Scotland for sharing today's image (original via BPotD Flickr Group Pool).

Known commonly as cuckoo flower or lady's smock, Cardamine pratensis is a plant of northern temperate meadows and wet open woods (the epithet pratensis means “of meadows”).

Once again, Raakel Toppila supplies the written portion of today's entry. – Daniel

Thank you to shotaku@Flickr from Missouri, USA for sharing today's image (original via BPotD Flickr Group Pool).

Senna hebecarpa, commonly known as wild senna, is a North American native plant growing on damp soils in Ontario, the east coast of the United States, south to Georgia and as far west as Wisconsin. Despite its vigour and mass production of seeds (of which only 10-30% are viable) in cultivated situations, this plant is considered endangered. Wild senna grows along roadways, disturbed areas, fields and the edge of streams. However, changes in hydrology, development of land and succession of secondary species are thought to be reducing its numbers.

Medicinal uses of Senna hebecarpa are extensive, ranging from curing cramps to administering for fainting spells. The extensive collecting of this plant for medicinal purposes (PDF) is also thought to contribute to the decline of this species in the wild.

Thank you again to UBC BG summer student Raakel Toppila for writing today's entry while I'm away. – Daniel

Thank you to yildizkonca@Flickr for sharing today's image (original via BPotD Flickr Group Pool).

Limodorum arbortivum is a common orchid of the Mediterranean region. Its leaves are reduced in size and therefore the species is thought to be partially mycoheterotrophic, relying on a fungal intermediate to draw nutrients from a photosynthesizing plant with no direct contact between plants. A different form of heterotrophy is parasitism, in which the plant (such as Rhinanthus minor has direct contact to the vascular tissue of a photosynthesizing plant. Heterotrophy is not uncommon among orchids, as they make up about a third of heterotrophic flowering plants. Of these heterotrophic orchid species, twenty completely lack chlorophyll.

Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel

Thank you to Dinesh from India (aka dinesh_valke@Flickr) for sharing today's image (original via BPotD Flickr Group Pool)

Couroupita guianensis is commonly known as the cannonball tree – a photo of the fruit reveals why. For in-depth information about cannonball tree, visit Couroupita guianensis via the Lecythidaceae Pages.

I'm still out in the field, but summer student Raakel Toppila has helped out by writing today's entry. – Daniel

Thank you to Stephen, aka stephenbuchan@Flickr from Edinburgh, Scotland for sharing today's image (original via BPotD Flickr Group Pool).

Rhinanthus minor, also known as yellow-rattle, occurs throughout the northern hemisphere, from Europe to Asia to North America. It is a hemiparasitic plant (much like mistletoe), obtaining some nutrients from a host plant or host plants, while still photosynthesizing. This contrasts with holoparasitic plants which lack chlorophyll entirely and therefore have no photosynthesizing apparatus. One study found haustorial connections (morphologically modified tissue which physically penetrates the host plant’s vascular tissue) in the roots of an individual Rhinanthus plant connecting to seven different host species. A rather greedy plant!

Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel

Thank you to Meg aka meggle@Flickr from the Silicon Valley in the USA for sharing today's image (original via BPotD Flickr Group Pool).

Like yesterday's white bat flower, black bat flower (or tiger's whiskers) is also native to southeast Asia. There are twelve species in the genus Tacca. In addition to southeast Asia, Tacca can also be found in tropical Africa, Madagascar and northeast South America.

Today's entry was written by UBC Botanical Garden summer student Raakel Toppila. – Daniel

Vicki of the eastern USA aka Vicki's Pics@Flickr is the photographer of today's image (original via BPotD Flickr Group Pool). Thank you!

Tacca integrifolia, also known as bat plant or white bat flower, is distributed throughout southeast Asia but can be observed elsewhere in the world where it is popular among conservatories and hobby horticulturists. Its peculiar “whiskers” are actually filiform bracteoles, or small bracts (modified leaves) which arise in the same axil as the flowers.

The unusual flowers of Tacca make one question why such an elaborate floral structure might have evolved. Often guesses can be made, much like Darwin predicted that the orchid Angraecum sesquipedale would have a pollinator with a proboscis long enough to reach its nectary. The later discovery of its pollinator in 1903, the hawk moth Xanthopan morgani praedicta, proved Darwin right.

As for Tacca, some have suggested the “deceit syndrome” as a reason for the evolution of the elaborate flowers. The resemblance of Tacca to decaying organic matter is cited as evidence that it is attempting to attract flies (sapromyiophily) to facilitate cross-pollination. Some traits associated with sapromyiophily include dark flowers and bracts, filiform appendages, trapping mechanisms and the absence of nectar – all traits that are possessed by Tacca species (Tacca integrifolia is also reported to have a musty smell). However, one study has found that Tacca species are primarily self-fertilizing and have no great need for pollinators. The as-yet unanswered question surrounding the elaborate flowers is discussed at the end of the linked article.

A scientific description of Tacca integrifolia is available via the Flora of China, while cultivation information is available from the University of Florida IFAS Extension.

Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel

Another thank you to Jacki of Oregon, aka jacki-dee@Flickr for sharing one of her photographs with us (original via BPotD Flickr Group Pool).

There's plenty of confusion surrounding the name of this plant; a glance at search engine results reveals Stachys 'Hidalgo', Stachys coccinea 'Hidalgo', Stachys albotomentosa, Stachys albotomentosa 'Hidalgo', and, for good measure, even Stachys hidalgo (which has never been scientifically published). I've opted to use the name tentatively accepted by the Royal Horticultural Society. The common name is scarlet hedgenettle or seven-up plant.

Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel

Words of thanks to xpeditions@Flickr for today's photograph contribution (original via BPotD Flickr Group Pool).

Most online references suggest the scientific name of chapparal yucca is Yucca whipplei, but recent DNA studies have reinforced the 1893 recognition by Trelease of Hesperoyucca as a separate genus. The Flora of North America's description of Hesperoyucca provides more information; the FNA entry on Hesperoyucca whipplei describes the species and includes a map of its distribution north of Mexico.