BPotD Archives being removed

Please do not link to these pages! The new site is up at http://botanyphoto.botanicalgarden.ubc.ca/. These pages are gradually being removed as we update the content on the new site.

Mar 19, 2015: ×Cystocarpium roskamianum

We are very grateful to have a guest entry from Dr. Carl Rothfels, a postdoctoral fern researcher at the University of British Columbia (and soon assistant professor at Berkeley). Dr. Rothfels and a team of researchers recently published the following: Rothfels, CJ et al.. 2015. Natural hybridization between parental lineages that diverged approximately 60 million years ago. American Naturalist 185:3(443-442). The first photograph is shared by another member of the research team, Harry Roskam, while the latter two photographs are courtesy of Carl. Thank you Carl and Harry, for the write-up and photographs!

Today's plant featured on BPotD is an extraordinary fern from the Pyrenees mountains in France, which goes by the rolls-off-your-tongue name of ×Cystocarpium roskamianum (seen in the first photo, courtesy of Harry Roskam). This species was first noticed growing in a nursery in the UK, by a fern taxonomist by the name of Christopher Fraser-Jenkins. While it may not look that unusual to us, Fraser-Jenkins noted that this innocuous-appearing plant shared characteristics of two groups of ferns--the fragile ferns (Cystopteris, exemplified in the second photo with Cystopteris fragilis) and the oak ferns (Gymnocarpium, exemplified by Gymnocarpium appalachianum). These two genera are very different from each other (at least to people who study ferns!): Cystopteris species have elongate leaves, short compact stems, a unique hood-shaped covering protecting the sori (the "spore dots"), and tend to grow in cracks in cliff-faces and other inhospitable habitats, whereas Gymnocarpium species have triangular leaves elevated on tall stalks, long-creeping underground stems (rhizomes), unprotected sori, and grow in rich soil on forest floors. Until recently, many taxonomists didn't think that they even belonged in the same plant family. How could two groups of ferns be more different? And as we all know, very different things are not able to successfully mate with each other...

Fraser-Jenkins, however, was not dissuaded--in pretty much every feature he examined, the plant from the nursery was intermediate between Cystopteris and Gymnocarpium and it didn't produce viable spores, which is another indication that it could be a hybrid. In researching the plant more, Fraser-Jenkins discovered it had been collected in the Pyrenees by a Dutch horticulturalist, Harry Roskam, who had brought it into cultivation (it grows vigorously and although it is sterile, it can reproduce rapidly via its long creeping rhizome, rather like a strawberry would). To honour the collector, Fraser-Jenkins formally described this plant in a new hybrid genus, as ×Cystocarpium roskamianum (the rules of botanical nomenclature stipulate that the genus name for intergeneric hybrids must start with the "×" symbol and then portions of each of the putative parental genus names, here "Cysto" from Cystopteris and "carpium" from Gymnocarpium).

But is ×Cystocarpium roskamianum really a hybrid between Cystopteris and Gymnocarpium? To answer this question, a team including Fraser-Jenkins, Harry Roskam, and researchers from Leiden University in the Netherlands, Duke University in the U.S.A, and the University of British Columbia in Canada, turned to the fern's DNA. If the fern was a hybrid it might be expected to have DNA sequences from both its parents, and that's exactly what the researchers found (to the great surprise of at least some of them): at a given gene, half the ×Cystocarpium sequences matched those from Cystopteris, and the other half were from Gymnocarpium. The DNA data were even more specific than that--×Cystocarpium is a hybrid between the cosmopolitan species Gymnocarpium dryopteris (which was the mother in the cross) and a European member of the Cystopteris fragilis complex (the father).

More astoundingly, the researchers were able to determine that the hybridization event probably happened only once, and very recently (maybe within our lifetimes) and that the last common ancestor of ×Cystocarpium roskamianum's parents lived approximately 60 million years ago. In other words, each of the parents had been evolving independently from the other for around 60 million years before the hybridization happened. Sixty million years is a very long time for two organisms to retain the ability to interbreed--typically that ability is lost within a few million years at most. To put this duration in perspective, the ancestors of humans diverged from those of chimpanzees a mere five or so million years ago; the hybridization event that formed ×Cystocarpium is roughly akin to a human producing a hybrid with a lemur or an elephant with a manatee. The fact that Cystopteris and Gymnocarpium retained some compatibility with each other after that amount of independent evolution raises interesting questions on how new species are formed, and how this process might differ in different groups of organisms. For example, ×Cystocarpium and the other reported cases of deep hybridizations tend to involve ferns and other plants that don't use animals to assist with fertilization. If there is something about the ecology or genetic structure of these species that allows them to retain reproductive compatibility among populations for longer than other groups do, and thus to form new species more rarely, could this explain why there are only around 10000 species of ferns (and approximately 1000 gymnosperms, 1200 lycophytes, 12000 mosses, 9000 liverworts, and 100 hornworts) compared to the nearly 300000 species of flowering plants?

Daniel adds: Another account of this research is available via NPR: "Weird" Fern Shows The Power Of Interspecies Sex.

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 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".

Feb 17, 2015: Cocos nucifera (dwarf cultivar)

Cocos nucifera

Adding the second in her series, Tamara Bonnemaison scribes:

We continue our series on extraordinary seeds with this image of Cocos nucifera, generously shared by Ahmad Fuad Morad@Flickr. The photo shows seedlings of an ambiguously-named "aromatic dwarf" cultivar of the coconut palm, taken in Sungai Pau, Malaysia. Thank you Ahmad!

The previous entry about extraordinary seeds featured Phoenix dactylifera, or the date, and today we discuss the coconut. I am tempted to turn this series into a cookie recipe--perhaps if I featured Triticum and Brassica napus (for canola oil) next, we could put together a tasty treat from those four ingredients! I have selected Cocos nucifera for this series as it has the second largest seed in the world, and it also has an unusual endosperm that provides us with both coconut water and coconut "meat". The prize for largest seed in the world goes to Lodoicea maldivica (a 2013 BPotD entry).

Like the previously featured date, the coconut fruit is a drupe, composed of a relatively thin exocarp (skin), and a dry, fibrous mesocarp that is about as different from the date's sweet flesh as possible. Below the mesocarp one finds the endocarp, the hard pit that surrounds the seed of all drupes. In coconuts, the smooth endocarp is polished and made into bowls, jewellery, and all manner of crafts. If you would like to make your own coconut endocarp bowl (you could call it a coconut shell bowl to whomever you give it to), here are some instructions. Before making a coconut bowl, it is recommended that you drain the coconut water by finding the coconut's soft "eye". Coconut endocarps have three eyes or germination pores, but only one of those is soft - the other two are often called the 'blind' eyes. Below the germination pores nests the single embryo, whose radicle will break through the soft eye when germinated.

The coconut's seed is well protected by its husk, and so its testa (seed coat) is very thin. Within the papery brown testa is the endosperm, the tissue that surrounds and provides nutrition to the developing embryo. In the coconut seed, the endosperm goes through a nuclear phase of development, during which it is present in liquid form. This "coconut water", has recently gained popularity as a nutrient-rich and refreshing drink, but I wonder if anyone would buy it were it labeled with its botanical descriptor: glass of nuclear coconut endosperm, anyone? As the embryo develops, the endosperm begins to form cell walls, and this cellular endosperm is deposited in layers against the testa, forming the coconut's "meat".

The white coconut meat is rich in fat, and can be eaten as is, or made into coconut milk and oil. In coconuts that have avoided being eaten or damaged, the germinated embryo will form an absorbing organ called a nursing foot, which swells into the cavity of the coconut and absorbs the nutritious endosperm over the period of about one year. These seedlings are still not quite safe--apparently the nursing foot is also called a coconut apple, and is quite delicious.

This article is focused on the coconut fruit and seed. If you would like to learn more about Cocos nucifera in general, read this great article by the The Private Naturalist - The Coconut Palm.

"If you could count the stars, then you could count all the ways the coconut tree serves us."--Phillipine proverb

Feb 16, 2015: Phoenix dactylifera

Phoenix dactylifera

Tamara Bonnemaison launches a BPotD series with today's entry. She writes:

We kick off a series about exceptional seeds with the story of a 2000 year old Phoenix dactylifera seed that was successfully germinated. Thank you to 3Point141@Flickr for submitting this lovely photo of a plant in the cultivated Medjool Group of Phoenix dactylifera. This photo was taken at Excalibur Fruit Trees Nursery in Florida, USA.

Phoenix dactylifera, or the "true" date palm, has played an important role for thousands of years of human history. In 1963, a stash of seeds "dating" (sorry, couldn't help myself) from AD 70 was discovered in Masada, a fortress in present-day Israel. In 2005, Sarah Sallon of the Hadassah Medical Organization managed to germinate just one of the ancient date seeds, and that seedling has now grown into a palm tree called "Methuselah". Date palms are dioecious, and it had been hoped that Methuselah would turn out to be female and produce fruit. Unfortunately, this date palm plant is now known to be male, and Sallon and her team will need to undertake careful breeding with modern date palms to produce females that are as close as possible to the ancient cultivated variety. Learn more about Masada and the discovery of these seeds from this National Geographic article: "Methuselah" Tree Grew From 2,000-Year-Old Seed.

The date palm is a 15-25m tall plant that is perhaps native to western India or southern Iraq, but a long history of use and cultivation has made it difficult for botanists to determine its exact place of origin. The fruit of Phoenix dactylifera is likely well known to all BPotD readers; this fruit was cultivated as a staple food and even to make date wine as early as 4000 BCE, and is still commonly eaten today (mmmmm, date squares). Other parts of the date palm may not be as sweet, but are equally useful. For example, palm hearts are used as a vegetable, the fibres can be woven to make a textile, the leaves are used to make mats, and the seeds produce a nutritious oil. For a more comprehensive list, view the Food and Agriculture Organization's Date Palm Products bulletin.

Although the date palm can be wind-pollinated, the standard practice in cultivation is to hand-pollinate the flowers The flowers are borne at the top of the tree and covered by a protective spathe that splits open when the flowers are mature. The fruit is a one-seeded drupe, which goes from green to yellow to reddish-brown as it ripens. This brings us to the seed. Date seeds are oblong, ventrally-grooved and have a small embryo. A hard endosperm made of cellulose surrounds the embryo, which is surrounded by the mesocarp (the fleshy, sweet part of the date) and finally the epicarp or exocarp (the date's skin). These are common features of the seeds of many fruits, and my search to uncover just what allowed Methuselah's seed to remain viable for two millennia revealed little.

Seed longevity is poorly understood by the scientific community, but is gaining more attention with the growing interest in (and need for) seed banks. A 2008 paper by Loïc Rajjou and Isabelle Debeaujon, Seed longevity: Survival and maintenance of high germination ability of dry seeds, sums up our current understanding of the different factors that affect seed longevity. Rajjou and Debeaujon report that seeds are able to protect themselves with their testa (seed coat), antioxidants, and by reducing their metabolic activity; seeds also have the ability to repair their DNA and decontaminate themselves. It is not clear which of the above qualities allowed the Phoenix dactylifera seeds found in Israel to remain viable for such an extraordinary long time, but it is likely that high levels of antioxidants present in date seeds contributed to this high longevity (date seeds are being studied for antioxidant qualities which could be used to improve human health and longevity). The date seeds also benefited from the dry, dark conditions present in Masada Fortress.

Science overload? Have a look at Shevaun Doherty's artistic exploration of the Methuselah date for an entirely different way of understanding Phoenix dactylifera.

Feb 13, 2015: Olsynium douglasii var. douglasii

Wildflower reports coming out of Washington state (via Oregon Wildflowers) note that one of the earliest flowers of the year, Douglas' grasswidow, is blooming along the Catherine Creek Trail. These photographs were taken three years ago at the same site in mid-March.

The first photograph displays the typical colour of the tepals, while the second image shows a nearby paler variant. Colours of the tepals can range from white to dark-purple. Though they are most often solidly-coloured, they can also display some variegation. Paul Slichter, who runs the Wildflowers of the Columbia River Gorge, has extensive photo-documentation of tepal colour variation in the species: Olsynium douglasii. Note that Paul also took photographs from the Catherine Creek site in early March of 2012 and observed a white-flowered variant, which I suspect had finished blooming by the time I visited.

Olsynium douglasii var. douglasii has been previously featured on Botany Photo of the Day, with an entry that discusses the name and a photograph of wild-collected material grown here at UBC Botanical Garden. I suspect it will be at least a couple weeks before we see any hint of flowers from our plants.

The Burke Museum also has additional images: Olsynium douglasii, while the Garry Oaks Ecosystems Recovery Team (GOERT) has propagation information and gardening conditions: Olsynium douglasii var. douglasii.

Feb 5, 2015: Viburnum tinus subsp. rigidum

Another entry written by Tamara Bonnemaison today. She writes:

The late James Gaither (aka JG in SF@Flickr) captured these two stages of Viburnum tinus subsp. rigidum, first in flower and then in fruit, at the UC Berkeley Botanical Garden. We are so grateful for the amazing collection of botanical photography that James Gaither has left for all of us to enjoy -- please do visit his Flickr site.

Viburnums have been featured many times on Botany Photo of the Day, including Viburnum betulifolium, Viburnum rhytidophyllum, Viburnum lantanoides, and Viburnum × bodnantense. It is no wonder the staff at BPotD are fond of viburnums. The shrubs and small trees of this genus are native to the temperate Northern Hemisphere, and many are commonly used in the gardens and landscapes of British Columbia and around the temperate world. The viburnums are loved by gardeners for their showy and often scented flowers, bright berries, and fall colour. The genus is quite variable, and one of the few characteristics shared by all members is that the fruits are drupes (stone fruit). Another characteristic that applies to nearly all viburnums is that they are reluctant to self-pollinate, so multiple plants of the same species (ideally not of the same clonal stock) should be planted in order to get a good fruit set.

Viburnum tinus is an excellent garden ornamental. It has an upright, oval to rounded form, and its evergreen leaves grow right down to the edge of the ground, making it particularly useful as a screen or hedge. The common name for this species, laurustinus, comes from its lustrous, laurel-like dark green leaves, which are complemented by pink buds that open to white, slightly fragrant flowers in winter. These flowers mature to the stunning black, metallic fruits shown in today's second photo. Laurustinus is quite easy to grow, being adaptable to most soil types and tolerant of full sun, salt spray, shade, and drought. Viburnum tinus is native to southern Europe, but the subspecies rigidum hails from the Canary Islands. I could not find a habit photo of the subspecies, but a lovely photo of Viburnum tinus growing wild in Sardinia was photographed by Gino Cherchi: Viburnum tinus.

Laurustinus may have some medicinal qualities; I found some sources that discussed its potential as a treatment for menstrual cramps, but cannot validate its efficacy (the same sources also said the berries could be toxic, so please don't try this out!). The most enthusiastic source of medical information about the viburnum genus is the 9th Edition of the Journal of Materia Medica, published in the 19th century. This source raves of the compound viburnin that the "Eclectic Physician" used to treat an array of diseases. This substance was derived from the bark of the high cranberry (Viburnum opulus), but is potentially also found in other species of Viburnum. Much more recently, the author of the blog Naturally Dyeing has used laurustinus to dye fabric (read about her attempts).

a place of mind, The University of British Columbia

 
UBC Botanical Garden and Centre for Plant Research
6804 SW Marine Drive, Vancouver, B.C., V6T 1Z4
Tel: 604.822.3928
Fax: 604.822.2016 Email: garden.info@ubc.ca

Emergency Procedures | Accessibility | Contact UBC | © Copyright The University of British Columbia