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

Mar 5, 2015: Ceanothus thyrsiflorus

Ceanothus thyrsiflorus

Tamara Bonnemaison, BPotD Work-Learn student, writes:

Thank you Dale Hameister@Flickr for this great photo of Ceanothus thrysiflorus taken in the Carmel Highlands of California, within its native range.

Ceanothus thyrsiflorus, or California lilac, is an evergreen shrub that is endemic to coastal California and southern Oregon. California lilac reaches a height of 1-6 meters and has showy blue flowers in dense panicles that bloom from March to May, giving this species its common name (it has no relation to the true lilacs, Syringa spp.). The attractive dark green foliage and flowers have made this species popular among gardeners in western North America, and a number of cultivars are now available. Ceanothus contains ~55 species, and many of these are particularly loved by native plant enthusiasts, who recommend planting Ceanothus for use by wildlife. For example, the flowers of Ceanothus thyrsiflorus support a number of butterfly and bee species, the seeds are eaten by quail and rodents, and the leaves are browsed by ungulates.

California lilac and other Ceanothus species play an important ecological role in Californian chaparral and forest ecosystems. Ceanothus species are among the first plants to colonize recently disturbed, particularly burned, sites. There are a few reasons why Ceanothus is an early seral species. Ceanothus are very hardy--they can tolerate drought, cold, extreme heat, and poor soil, but they have little ability to tolerate shade. Also, the seed coat of Ceanothus seeds are physically opened by heat, so fire stimulates the germination of seeds that have been lying in wait for just such an opportunity. On sites with adequate soil depth and moisture to support forests, Ceanothus thyrsiflorus will dominate for a few decades, but will eventually begin to get shaded out by conifers and other trees. Over the few decades of the Ceanothus' reign, it will have improved the soil, accumulating large amounts of biomass and fixing atmospheric nitrogen, and will also have provided one of the best available food sources for deer and other wildlife. The United States Department of Agriculture produced an excellent report on the ecological role of species of Ceanothus (PDF).

A few other tidbits of information about Ceanothus thyrsiflorus: the blue flowers can be used to make a green dye (though why green rather than blue?), and all parts of the plant can be crushed and worked into a lather to use as a gentle soap, as the plant contains saponins.

Mar 3, 2015: Greyia sutherlandii

Greyia sutherlandii

A quick entry from Tamara Bonnemaison today. She writes:

Mike Bush (aka aviac@Flickr) recently shared this colourful photo of Greyia sutherlandii, which was taken at the Leaning Pine Arboretum in California, USA. Thanks Mike for brightening our day!

Greyia sutherlandii, or Natal bottlebrush, is a small tree endemic to South Africa that is, for reasons well demonstrated by today's photo, popular among gardeners in warm, dry climates. The flowers--tightly-packed racemes--emerge in late winter before the leaves, looking particularly bright and stunning against the silvery bark. Towards the end of the flowering period, the leaves emerge bright green and then later age to a darker green colour.

Its genus and species name both honour male colonialists who spent time in South Africa. Sir George Grey was a governor of the Cape Colony, while Dr. Peter Cormack Sutherland, a Scottish physician, was the first to deliver a specimen of this species to England in 1850. I imagine that the African people noticed and used this beautiful tree long before Grey and Sutherland ever stepped foot in Africa. I found one account that the soft, light-pink wood was traditionally used to make cutlery. This species also has a number of common (non-English) names, including isiDwadwa, inDalu, and uBande in Zulu, and umBere-bere in Xhosa.

Feb 27, 2015: Magnolia sprengeri 'Eric Savill'

Magnolia sprengeri 'Eric Savill'

Magnolias are well into bloom here at UBC Botanical Garden. I did make the prediction in the entry on Iris unguicularis a month ago that "it may be one of those years where the first magnolias blossom in early March, if not late February". One might argue I was too conservative, as the first blossoms opened prior to February 20. In any case, the Garden launches its seasonal opening tomorrow, for what will be both a beautiful and busy day.

I chose today's image for its illustration of how cameras capture colours, and why it isn't always useful to rely on photographs if one wants to know the "true" colour of an object. It's a contemporaneous subject, as there seems to have been much debate about a dress the past couple days: "The Science of Why No One Agrees on the Color of This Dress" (via Wired).

In today's photograph, those parts of the unfurling flower in shadow have a bluish-cast, including not only the tepals but also the fuzzy hairs on the distant perules (or bud scales). Those parts exposed directly to the rays of the sun have a daytime "white" light to them, which is most noticeable on the forefront line of those fuzzy hairs, though some tepals have a bit of daytime light on them as well. To make matters more confusing, some of the tepals are side-lit so that they are glowing with the light that has diffused through the tepal. For another photograph of a flower from this particular plant, this time in late-evening golden light, see this previous entry on 'Eric Savill' magnolia. Different lighting conditions, different colours.

For scientific photographs and scans, colour calibration charts or cards are often inserted into the images to permit later correction to standard colours under standard conditions. For example, see this specimen of Corydalis aurea from the UBC Herbarium, but do note that while the colour calibration chart is present, the image is not yet calibrated--e.g., the black in the chart is not a true black.

For more on Magnolia sprengeri 'Eric Savill', either read the linked entry above or see the RHS page on the cultivar: Magnolia sprengeri 'Eric Savill'. The RHS site contains yet another photograph with a different rendition of blossom colour (I'd guess a scanned slide of a flower photographed indoors under a mix of indoor lights).

Feb 23, 2015: Aerides odorata

Tamara Bonnemaison concludes the exceptional seeds series with the following write-up:

Today the smallest seeds in the world--those of the orchids--are highlighted. I have chosen to feature this photo of the beautiful Aerides odorata, taken by Azhar Ismail (aka abiom.orchid3@Flickr), to serve as an example to learn about the minute wonders of the orchid seed. Thank you, Azhar! The accompanying illustration of orchid seeds is by J.G. Beer, published in 1863. This drawing is available via Wikimedia Commons.

Aerides odorata is an oft-admired epiphytic orchid species native to from India, Bangladesh, and Malaysia. It is one of the most profuse bloomers in its genus; the white and pink flowers have a delightful odour (hence the species name). The plants are prized by the floral industry. Like other orchids, Aerides odorata has extremely small seeds, measuring only 0.2mm in length. This is still four times larger than the smallest seed identified to-date, which belongs to another orchid, Anoectochilus imitans. To the naked eye, though, the seeds of both species would look like specks of dust. Royal Botanic Gardens, Kew has an informative article about orchid seeds--the photos of magnified orchid seeds are well worth a peek.

Why are orchid seeds so tiny? Orchids have a fascinating reproductive strategy; in order to germinate and grow, orchids in nature must be colonized by a specific mycorrhizal fungus. Having tiny seeds allows Aerides odorata and other orchids to produce millions of seeds at a very low energetic cost, making it more likely that some of those seeds will be deposited in close enough contact with an appropriate fungus. Most orchid seeds are small and light enough to float along wind currents, assisted by a one-cell thick testa that forms a balloon around the miniscule embryo. J.G. Beer's illustrations shows this balloon-like testa around many of the seeds depicted. Most orchid seeds have extremely small food reserves in the embryo, and have foregone the endosperm altogether. They do not have the energy reserves required for germination and seedling growth, and must instead rely on their fungus to pass along carbon and minerals. The orchid seedlings are entirely dependent on this relationship until they are able to photosynthesize, and may continue to benefit from their mycorrhizal association during their entire lifespans. An article on the University of Sydney's Fungal Biology website states that it is unclear what, if anything, the fungus receives in return.

The reproduction strategy employed by Aerides odorata and its kin has clearly worked well. The Orchidaceae is one of the two largest families of flowering plants (the other being Asteraceae), containing well over 25000 accepted species. There are also about 100000 hybrids and cultivars, which have been produced by gardeners and botanists enthusiastic enough to brave the strange world of orchid reproduction.

Feb 20, 2015: Merremia discoidesperma

Merremia discoidesperma

Returning to the exceptional seeds series, here is the fourth entry by Tamara Bonnemaison:

The species with the longest-recorded drift range in the world, Merremia discoidesperma, is the subject of today's entry. Susan Ford Collins (aka jungle mama@Flickr) provides this gorgeous photo of a Merremia discoidesperma seed that has been colonized by tiny corals on its long drift through the ocean from Mexico or Central America to Miami Beach.

Merremia discoidesperma or Mary's bean, is an uncommon woody liana found only in Mexico, Cuba, Guatemala, Costa Rica, and Hispaniola. Mary's bean is little known in its plant form--its real claim to fame is for its seed. In fact, the seeds of Merremia discoidesperma were known and described for many years before the plant. In 1605, the Flemish botanist Carolus Clusius published the first drawing and description of a Mary's bean seed, labeling it as a "stranded seed", but the species did not receive its first binomial name until 1889, when John Donnell Smith named it Ipomoea discoidesperma. Mary's bean seeds are a conspicuous but rare find on beaches far from their origin, and they have been kept as treasured keepsakes, passed from mother to daughter, by people who have never seen the plant. Aside from the novelty of finding a beautiful seed washed up on the beach, the seeds from the Mary's bean plant have a hilum in the form of a cross, giving them particular religious significance for some.

Drift seeds are not common. Of all the plant species found on our diverse and wonderful planet, only around 250 are specifically adapted to drifting at sea. Mary's bean is exceptional even within this small group, as its seeds remain buoyant for an unusually long time--up to three years. The limited distribution of the species makes it possible to track the distance that it has traveled. Mary's bean seeds that wash into the Caribbean and Atlantic can be found as far away as the Norwegian coast, carried a distance of 9500km by the Gulf Stream. Seeds that end up in the Pacific Drainage Region may travel even further, with records of Mary's bean seeds washing up in the Wotho Atoll in the Marshall Islands, about 11000km from their originating site. However, it is possible that seeds from other species have drifted further. For example, sea beans, or the seeds of Mucuna holtonii are likely to travel even further than Mary's bean seeds, but because Mucuna holtonii has a more extensive distribution than Merremia discoidesperma, it is impossible to know exactly the distance traveled.

In order to enter the "drift seed club", seeds must not only be able to float, but must be able to do so for a period of at least one month. There are a few approaches that seeds take in order to float: some have cavities within the seeds; others are made buoyant through a corky or light-weight fibrous layer; and still others are thin enough that they float on the water's surface. In the case of Mary's bean, a cavity at the centre of the embryo provides the buoyancy needed for the seed to cross oceans. Despite its ability to disperse seed across the world, Merremia discoidesperma can only be found in a very limited geographic area. This was a source of puzzlement to the researcher Charles R. Gunn, who speculated that insect attack keeps this species from establishing in seemingly suitable environments where its seeds routinely wash up.

Feb 19, 2015: Arctostaphylos pallida

This will be a one-day interlude to the exceptional seeds series today, while we sort out a small issue with the next entry. However, the author for this piece is again Tamara Bonnemaison, who writes:

Today's Botany Photo of the Day features Arctostaphylos pallida, or Alameda manzanita, a rare species photographed by John Rusk@Flickr in Berkeley's Regional Parks Botanic Garden (Tilden Regional Park). A close-up of the flowers and leaves is provided by Pete Klosterman (aka Oaktown Pete@Flickr), and his photo was taken at the Sobrante Ridge Regional Preserve in Richmond, California. Thank you John and Pete! I have a fondness for plants that survive difficult conditions, and seeing the beautiful twisted branches of this Alameda manzanita growing on tough rocky ground reminded me of the saying, "What doesn't kill you makes you stronger". As I enter the middle of the university semester, this quote is feeling more and more relevant to my own life....

Unfortunately for Arctostaphylos pallida, it has a restricted range and little ability to adapt to the changes that humans have made to the California landscape. This species is found only in the counties of Alameda and Contra Costa, just east of San Francisco Bay, California. The species is state-listed as endangered. Alameda manzanita requires exacting site conditions; barren, siliceous soil combined with a regular supply of summer fog rolling off the Bay to keep it irrigated during the dry season. Most importantly, Alameda manzanita is a fire-obligate species; its seeds will only regenerate on sterile, barren soils following fire, and mature plants are out-competed by understory species if the timespan between fires extends for more than 50 years or so. Fire suppression, invasive species, and possibly also a root fungus have resulted in a decline in this already uncommon species, and there are now an estimated 9 populations remaining. It seems the lesson here is that surviving difficult conditions only counts for so much--a species may also have to handle changing conditions to make it in the modern world as well.

Arctostaphylos pallida is a tall evergreen shrub with white, bell-shaped flowers and red fruits. The specific epithet, pallida, does not refer to the colouring of the flowers, but is instead a reference to the glaucous bloom coating the leaves, which is easily rubbed off. The leaves are a distinguishing characteristic of the species; sessile, heart-shaped leaves that clasp or nearly-clasp the branches are unique to this Arctostaphylos. Like many other members of its genus, Alameda manzanita has orange-red peeling bark, but it lacks the basal burl that permit related species such as Arctostaphylos glandulosa subsp. glandulosa to re-sprout vigorously after a fire.

Feb 18, 2015: Alsomitra macrocarpa

Alsomitra macrocarpa

Tamara Bonnemaison is again the author for her series. She writes:

The third species to make into the exceptional seeds series is Alsomitra macrocarpa. Scott Zona@Flickr photographed this amazing winged seed at the Bogor Botanical Garden in Indonesia. Scott posted this lovely text along with his photo (follow link to read his whole quote): "I was transfixed as I watched dozens of winged seeds of Alsomitra macrocarpa glide to the ground in broad, lazy spirals. The seeds spilled out from a fruit hanging on the liana climbing on one of the enormous old trees in the garden. All the principles of aerodynamics as they relate to seed dispersal were manifest in that one lovely moment."

In an article published by the Fairchild Tropical Botanic Garden, today's photographer Scott Zona describes wind dispersal in seeds. Although different plants use different strategies, explains Zona, all wind-dispersed species are aiming to maximize their time aloft, which directly increases their dispersal distance. Some species use parachutes or plumes to float along air currents. Others are so small and light that they become a part of the fluid movements of air. The third strategy is to develop wings, and no seed has wings that can rival those of Alsomitra macrocarpa, or mitra.

A member of the squash family, mitra is a long liana that grows up into the canopy of the forests of Java, Indonesia. It is quite famous for its 13cm wide, gliding seeds that have inspired a number of aircraft builders. The seeds of the mitra have the ability to remain stable during flight, despite having no moving parts to adjust to changes in air current or other disturbances. This characteristic was noticed by the aircraft developer Igo Etrich, who developed the Etrich Taube, one of the world's first gliders and the first military aircraft to be mass produced in Germany. The wings of the Taube provided excellent stability for the aircraft, making it well-suited to observational flights. The Alsomitra macrocarpa seeds in flight look like little aircraft--you can watch them soar over the Javan tree canopy in this short BBC video: Vine seeds become "giant gliders".

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