Pandanus tectorius is a very common sight on the Hawaiian islands. It is found in tropical Asia, Australia and on many Pacific Islands. It is generally thought to be indigenous to Hawaii, but additional varieties may have been brought by Polynesian explorers. It is sometimes given the amusing moniker, tourist pineapple, and I must admit I heard the words, "oh look--pineapples", from tourists looking at the plant. The background of the photo shows the dramatic topography of the Nā Pali Coast. By my estimation, the verdant peaks in this view rise around 250 metres (800 ft).

The shrubs or small trees are variable, generally growing 4-14 metres (13-46 ft) tall with similar dimensions of canopy spread. Pandanus tectorius is dioecious, i.e., male and female flowers appear on separate plants. The single trunk of the plant reaches a height of around 4 metres before branching. It is supported by a dense skirt of prop roots at its base. Long strap-like leaves are spirally arranged. As the plant grows in height, lower leaves fall off. Due to the spiral arrangement of the leaves, the now-bare trunk is left with a twisted appearance, leading to another common name, screwpine.

Pandanus tectorius is one of the most important plant resources to Pacific Island peoples. The species is used extensively for weaving, food and medicine, craft making, ornament, dye and other purposes. Both the seeds and fruit are eaten. Many varieties of the plant have been selected to best serve these cultural needs. Some provide better tasting fruit, others are more suitable for weaving.

Two pages of photos showing many aspects of the tree can be seen on Plants of Hawaii. To learn more, excellent articles describe the species at the Culture Sheet and at Pacific Island Agroforestry (PDF 1.82MB).

Gentiana prostrata, or pygmy gentian, is a low-growing 3-7cm (to 3in.) tall annual. Its preferred habitat is wet meadows of high altitudes or tundra. Conflicting accounts of its range abound; the Flora of China account does not mention South America, nor does The Jepson Manual. Though both of these cite Eurasia and western North America, the absence of South America is curious. The species, after all, was collected by Darwin near the Straits of Magellan during the Voyage of The Beagle. Perhaps it is because the species was thought to have been dispersed to South America by albatross (might be a subscription-only link)?

Gentiana prostrata was scientifically described by the Bohemian-born botanist, Tadeáš Haenke. To read more about Haenke, an excellent compilation of articles about his life are presented in the Botanical Electronic News, Issues 287 and 288.

The question was asked by Mary Hamilton in the comment section to Gentiana calycosa as to whether one of the "closed gentians" (that can be seen in New Jersey) would be featured. Mary was probably thinking of Gentiana andrewsii (see more photos), but there are other "closed" gentians and gentian relatives, including Gentianella quinquefolia and today's species, Gentianella hirculus.

Gentianella means "dwarf gentian" -- today's species reaches only 10cm (4in.) tall. The centre of diversity for the genus is South America, though the two hundred plus species are distributed throughout most temperate regions of the world. Gentianella hirculus is considered endangered by the IUCN Red List, with only 12 populations of plants remaining in the wild. Threats include grazing and, paradoxically, visitors to the park where most (all?) plants reside.

"Closed" gentians are either known or assumed to be pollinated by long-tongued bees (example). Take that, Gene Simmons.

These images were taken in mid-July 2009 northeast of the Lick Creek Campground in northeast Oregon, part of the USA's Hells Canyon National Recreation Area. I believe this particular plant was spotted by my traveling companion, and I was quite delighted to see it in person, as I had only known it from books previously.

A close relative of Frasera speciosa, white-stemmed (= albicaulis) frasera occupies a different habitat. Where Frasera speciosa is a species typically found in moist alpine or subalpine meadows, the much shorter (to 75cm / 30in) Frasera albicaulis tends to be a species of dry, open sites (including sagebrush-steppe). In this case, it was growing roadside in an open area heavily dotted with pieces of gravel with a low-growing species of Allium (the purple spots in the background of the second photograph).

While I was intrigued most by the unusual colours of its flowers, others have been more interested in its roots. A 1968 paper by Stout et al. in Tetrahedron explains the investigation of the roots for the presence of xanthones: Xanthones of the Gentianaceae--II *1: Frasera albicaulis Dougl. ex Griesb.. While many xanthones (i.e., molecules using xanthone as a central core molecule) were and are produced synthetically, fifteen different kinds were found in the roots of Frasera albicaulis -- ten of which had previously not been known to occur in nature. Xanthone proper is used in the production of insecticides, while some of the synthetic xanthones are involved in the manufacture of UV-resistant films.

Frasera albicaulis is native to western North America. For more photographs and a description of the species, see the Burke Museum's page: Frasera albicaulis.

This little annual or biennial, growing from 5cm to 60cm (to 2ft.) high, is recognized by J.M. Gillett as being a subspecies of Gentianopsis detonsa, i.e., Gentiana detonsa (Rottb.) Ma subsp. yukonensis (J.M. Gillett) J.M. Gillett (as noted in William J. Cody's encyclopedia Flora of the Yukon Territory. If one accepts this subspecies as being valid (and few other references do), then this is a taxon that is "endemic to the valley of the Yukon River and its tributaries in central Alaska and southwestern Yukon Territory", where it grows in "forest meadows and subalpine heathland". It's also noted that it grows in disturbed situations. Accordingly, this particular plant was photographed along the highway northwest of Haines Junction, in a small roadside meadow ringed by trees that had (at some point in the past) been disturbed by bush roads.

On the other hand, if one doesn't recognize this as a subspecies only found in Yukon and Alaska, then it is folded into a species with a much wider distribution: at the least, much of northern North America--and sometimes more, including south through the Rockies into Utah, New Mexico and Nevada. In addition to North America, the species is also found in Iceland, Norway and Russia.

I am partial to fringed gentians as they are one of the first plants I could recognize that weren't "always there" (and by that I mean they weren't a tree or shrub). It was a special trip to go with my mother once every year or two (sometimes we missed them) to see the small patch of fringed gentians that grew in the ditch a few kilometres from my home.

The common name Rainier pleated gentian hints at a western North American distribution, and that is indeed the case, with a range from British Columbia to California and east to western Wyoming (as an aside, I know some of you get impatient with photographs from western North America, but it's what I have on hand--there'll be at least one photograph from elsewhere in the world later in the series). Other common names, as you might surmise, rightly suggest it is a species of subalpine and alpine environments along streams, wet meadows and bogs.

The epithet calycosa means "full calyx", and I'm afraid I don't know why that is noteworthy in comparison to other gentians.

Cultivation of Gentiana calycosa is possible, but according to the Encyclopedia of Northwest Native Plants for Gardens and Landscapes, it is "a perennial for the determined, patient gardener". This is due to its preference for moist, yet well-drained soils--in other words, trying to replicate a mountain environment with a cool stream or seep.

Another intriguing fact one can glean from their paper is that Frasera speciosa is monocarpic, meaning it flowers and fruits in only the last year of its life, spending the remaining decades and years as a mass of leaves. With a range of age before flowering, (minimum age roughly 20 years), how do individual plants ensure cross-pollination? Taylor and Inouye published a subsequent Ecology paper on this topic in 1985, Sychrony and Periodicity of Flowering in Frasera speciosa (Gentianaceae). In short, mature individuals within a population will synchronize flowering in 2-4 year intervals, so that there are peak years (to the extent of >90% of the mature individuals flowering) and low years. What prompts the synchronization is not detailed in these papers, but in some instances, the evidence suggests environmental factors.

One last point: why is it important to know the life-cycle of a plant? In the case of Frasera speciosa, knowledge about its life-cycle can help inform those who use it for economic purposes, e.g., harvesting its roots for medicinal purposes. There is a significant difference in what can be sustainably harvested from a species with a 2 year life-cycle vs. a species with a 20-60 year life-cycle.

Frasera speciosa is known by a suite of common names: monument plant, green gentian, and elkweed (follow links for additional details and photographs).

I believe today's species is the Oregon native Monterey centaury (Zeltnera muehlenbergii) and not the close-in-appearance, and introduced-to-North America, common centaury (Centaurium erythraea). One of the key identifying characteristics between the two species is whether or not the individual flowers always have two bracts at the base and are sessile (emerging directly from the stem) or whether some flowers are pedicellate (having pedicels, or short stalks connecting the base of the flower to the stem). I have other, poorer photographs that seem to show some pedicellate flowers, so my conclusion is Zeltnera muehlenbergii as opposed to Centaurium erythraea (but I welcome any discussion on the matter). Another point in favour of it being Zeltnera muehlenbergii is that it was growing at the edge of a wet meadow and pond, whereas Centaurium erythraea is typically a species of dry to mesic conditions (though it will also grow in wet places).

Most references on the species Zeltnera muehlenbergii will use a synonym, Centaurium muehlenbergii. The name change to Zeltnera occurred in 2004 with Guilhem Mansion's Taxon paper on "A New Classification of the Polyphyletic Genus Centaurium Hill (Chironiinae, Gentianaceae): Description of the New World Endemic Zeltnera, and Reinstatement of Gyrandra Griseb. and Schenkia Griseb.". With this taxonomic treatment, the genus Centaurium changed from about 30 species occupying mainly north temperate regions with one species extending to Chile and another to Australia, to a genus comprised of 20 Eurasian species. The species of Centaurium found in the western Americas were moved into the newly-erected genus, Zeltnera.

Monterey centaury is native to western North America from British Columbia to California. Had I found this species in British Columbia, it would have been a bit of a coup as it is a red-listed species (i.e., threatened or endangered) found only in a few locations. However, along the coast of southern Oregon, it is fairly common.

If I recall correctly, it had a sweet fragrance.

Silver tree (the epithet argenteum means "silver") or witteboom is native to the Cape Province of South Africa. As should be evident from the second photograph in particular, reflective silvery hairs covering the surfaces of the leaves are responsible for the common name and epithet. The Protea Atlas Project has this explanation for the hairs on the leaves of Leucadendron argenteum: "...[the] thousands of hairs which cover the leaf...protect the plant from desiccation and herbivory. The intensity of the sheen [of the leaves] varies with temperature and is most pronounced in hot, dry weather when the hairs lie flat on the leaves...During wet weather the hairs stand more erect...and the leaves are relatively drab."

Leucadendron argenteum is considered vulnerable by the IUCN Red List, noting that remaining populations of the species are threatened by the development of Cape Town, too-infrequent fires, alien invasive species and clearing of land for tree plantations. Fortunately, the largest population of the species is protected within the land maintained by Kirstenbosch National Botanical Garden, allowing for management and monitoring.

An excellent description of this species, including its local distribution, the origin of its name and other historical information, and use in cultivation can be read on Plantzafrica: Leucadendron argenteum.

Cahaba Indian paintbrush can be found only in one county in Alabama, Bibb County. Since 1992, botanist James Allison has explored the area where Castilleja kraliana grows and exclaims, "Bibb County is blessed with an even greater number of rarities than anyone had imagined. It appears, in fact, to support the most significant diversity of rare plant species of any county in the temperate Southeast!"

Why so biodiverse? The area where Castilleja kraliana is found (along with at least sixty other taxa of conservation concern) has a set of characteristics which foster high levels of biodiversity: 1) it is mostly rural; 2) it is geologically diverse (it is the intersection of 3 geographic regions, each with its own associated flora and fauna); and 3) it contains rocky outcrops with unusual soil chemistry. The rocky outcrops are known as glades; nearly treeless, open areas with little soil. What soil does exist is the result of breakdown of the underlying Ketona Dolomite. Dolomite is a rock composed of carbonates of calcium and magnesium, but it is often filled with impurities (roughly 40%). Ketona Dolomite is special in that it is nearly pure, with impurities ranging in the 2% range. Without the impurities to balance out the magnesium carbonates, the soil that is formed from the dolomite is consequently high in magnesium concentration. Although important to the growth of plants in small amounts, high concentrations of magnesium prevent the uptake of other nutrients, i.e., it becomes toxic to plants. Only specially adapted plant species can withstand the combination of high magnesium and little soil, leaving, as Allison states, "a community of drought- and magnesium-tolerant plants able to evolve in the absence of competition from more generally adapted types. The presence of multiple newly discovered species, several of them with seemingly primitive features, as well as the occurrence of others whose nearest known locations are hundreds of miles distant, suggest that this plant community is an ancient one."

Thanks to the discoveries of Allison and others, The Nature Conservancy has helped create a preserve, the Kathy Stiles Freeland Bibb County Glades Preserve, to protect the most significant areas of biodiversity. Similarly, in 2002, the adjacent Cahaba River National Wildlife Refuge was established.

To read more about this intriguing area, visit Allison's web site to read A Botanical Lost World in Bibb County, Alabama or Vascular Flora of Ketona Dolomite Outcrops in Bibb County, Alabama (published originally in Castanea, 66:1-2 (154-205)).

Thank you to Kathleen Garness for submitting today's photograph and write-up to help continue the Botany Photo of the Day series on biodiversity success stories. Kathleen is part of Chicago Botanic Garden's Plants of Concern program, and Cypripedium candidum is one of the species she monitors. Kathleen writes:

Commonly known as white lady's slipper, Cypripedium candidum is a species of mesic calcareous prairies and fens, preferring a soil pH of 7.2 to 7.8. In the US Midwest, bloom time ranges from early May to mid-June. Most remaining populations (with a few notable exceptions) are very small, and it is a rare sight to visit a rich prairie in May and marvel at the sight of hundreds of these tiny orchids with their dazzling white pouches like little elven shoes dancing in the sunlight. The plants range in size from 10cm to 42cm in height. The greenish-yellow, tan-striped sepals range from 15mm to 46mm in length, with a white lip, from 17mm to 35mm in length, occasionally veined in purple and/or spotted on the interior rim with purple.

In Illinois (and other states as well), most of those prairies have long been plowed under, but a few remnant areas used for grazing, too wet to plow, or adjoining railroad right-of-ways, had survived development's relentless spread. Since 1970, with the establishment of the Illinois Natural Areas Inventory, a few dozen populations in 21 counties have been documented and monitored in Illinois. It has also been recorded from Manitoba, Ontario (where it is protected under Ontario's Endangered Species Act), Saskatchewan, Alabama, Indiana, Iowa, Kentucky, Maryland, Michigan, Minnesota, Missouri, Nebraska, New Jersey, New York, North and South Dakota, Ohio, Pennsylvania, and Wisconsin. In Illinois, Cypripedium candidum is state-listed as "threatened", downlisted from endangered several years ago.

A long-lived perennial, it can establish clumps of up to 80 blooming stems under good conditions (no invasive shrubs to shade it, little disturbance from mechanical, biological or human impacts, sufficient seasonal water to sustain the mycorrhizal associates essential for recruitment). But unlike other, less conservative species, it shows no tendency to invade disturbed areas, so it is threatened with extinction in Illinois and elsewhere unless conservation efforts succeed. This species has the highest light requirements of any of North America's native cypripediums, so intensive volunteer resources have been devoted to preserving it in its remaining habitats, removing aggressive or invasive brush (primarily dogwood (Cornus sp.), buckthorn (Rhamnus cathartica), Russian olive (Elaeagnus angustifolia), as well as tall aggressive or invasive forbs and grasses such as tall goldenrod (Solidago canadensis), sawtooth sunflower (Helianthus grosseserratus), common reed (Phragmites australis) and reed canary grass (Phalaris arundinacea).

Daniel adds: two points of BPotD interest: first of all, BPotD reader Patrick Gracewood on his sculpture blog Shadows on Stone made mention of the Guaiacum sanctum featured on BPotD a few days ago in a blog posting: Sculpture and Lignum Vitae.

Secondly, I think we have enough contributions now for this series. However, we'd really welcome contributions for February's thematic series, "Biodiversity and Sports". If you have photographs in the BPotD Flickr Pool that might work, please tag them with "iybfeb". Or send them along to me -- I suspect there will be a lot of wood and fibre species used in sports equipment, but if you can put on your lateral thinking caps, I'd be interested in tangential possibilities as well.

Another thank-you to Eric in SF for contributing today's photo and helping continue our series on conservation success stories (original image | Botany Photo of the Day Flickr Pool). Much appreciated!

Epidendrum ilense is an epiphytic orchid, endemic to the Montanas de Ila in Ecuador, a range of hills on the western side of the Andes (in Pichincha Province). It was discovered in 1976 by Dr. Calaway Dodson. This striking orchid reaches 30 cm in height. Inflorescences are borne both apically and laterally, and can occur throughout the year

Added to the IUCN Red List of Threatened Species in 1997, this species has never had a conservation status other than endangered. Upon returning to the site of initial discovery after six months had passed, Dodson found that the area had been completely deforested and the known remaining wild individuals destroyed. Dodson's initial collections of this species were cloned via meristem tissue at the Marie Selby Botanical Gardens, as initial attempts to self-pollinate the plants were unsuccessful. Researchers began working under the assumption that the species may be self-sterile and preserved tissue culture. It was one of the first species to be propagated successfully at the Eric Young Micropropagation Centre at Marie Selby. Viable seed was eventually produced, though, and crosses were made to increase the genetic diversity. Seeds and / or seedlings were subsequently distributed to botanical gardens and scientific institutions worldwide. They were also sent to every orchid grower willing to donate $100 to either the American Orchid Society or the Marie Selby Botanical Gardens, and individuals of this species are now widely distributed among collections. Some plants have been introduced to the Rio Palenque Reserve in Ecuador, not far from the Montanas de Ila. It is hoped that they will become established and supplement the recently-discovered second (small) wild population of this species.

Commonly known as lignum vitae ("wood of life") or holywood, Guaiacum sanctum is native to the Florida Keys of the southeast USA, Central America and the Caribbean. It is the national flower of the Jamaica. Lignum vitae is an extremely slow-growing, multi-trunked, broadleaf evergreen which can reach 9m to 12m, but because of its slow growth and heavy harvesting, it is more commonly found at 2.5m to 3.5m tall in the wild.

A number of times each year, the leathery, dark green leaves are offset by large clusters of deep blue flowers. The old flowers fade to a light silvery-blue, and create a "shimmering halo" over the rounded canopy. Flowers are followed by small, heart-shaped, yellow fruits, which sometimes appear at the same time as the blue flowers--a stunning sight. The wood of this genus is famous for its density, durability and strength. It is the hardest trade wood measured via the Janka hardness test and will sink in water. This dense wood was once popular for use in propeller shafts on steamships, gears and mallets.Lignum vitae was also harvested, somewhat notoriously, for medicinal purposes. Purportedly, during his travels in the New World, Christopher Columbus picked up both syphilis and its cure--a concoction of lignum vitae!

All species of the genus Guaiacum are now listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora. According to the World Conservation Monitoring Centre, Guaiacum sanctum is considered endangered. It is similarly listed on the International Union for Conservation of Nature's Red List of Threatened Species. Population estimates suggest less than 2500 mature specimens in the wild, and those remaining individuals still face a rapid decline. Decline is principally due to deforestation and exploitation for human uses. In Central America and Florida remaining populations are threatened with habitat loss or exploitation, e.g., in Guancaste in Costa Rica, El Salvador, and Florida Keys. Conservation groups in both Costa Rica and the Bahamas have been successful in lobbying local authorities to ban sale and export of lignum vitae by establishing protected areas in its natural range. Despite its slow growth rate, propagation of Guaiacum sanctumis fairly easy. Current research suggests its use in rehabilitating degraded sites within its natural range.

Lindsay Bourque is responsible for today's write-up. Lindsay writes:

Thank you to Lorena Moore, aka leonfangs@Flickr, for submitting today's photograph (original image | Botany Photo of the Day Flickr Pool) to launch our 2010 series on biodiversity.

The pima pineapple cactus is a small hemispherical cactus (10-18 cm in height). It is native to the Sonoran Desert of southern Arizona and northern Mexico. Coryphantha scheeri var. robustispina is a rather uncommon lower elevation cactus with prominently grooved, thick tubercles. Older tubercles toward the bottom of plants can differentiate to form new plants if the parent plant dies. Silky, pale yellow flowers burst into bloom in July with the onset of the monsoon season in the Sonoran Desert. The flowers are quickly followed by sweet, green fruits, which are an important food source for desert fauna.

Added to the United States Endangered Plant Species List in 1993*, threats to this taxon include loss of habitat due to urban development, off-road vehicle use, road construction, livestock grazing, and agriculture & mining. Nonnative grasses are also altering its habitat, preventing establishment of new individuals. Buenos Aires National Wildlife Refuge has a prescribed burn management regime to control these nonnative grass species. Illegal collecting is also a problem, despite state protection laws. Approximately only 21 populations of pima pineapple cactus remain*.

In 1998, on behalf of a coalition of 31 environmental groups, the Center for Biological Diversity drafted the Sonoran Desert Conservation Plan. Encompassing nearly 6 million acres, this large-scale, regional habitat conservation plan is intended to end uncontrolled development in Pima County by establishing a process to conserve large areas of desert. It manages development and open space in southern Arizona to protect the pima pineapple cactus and 22 other endangered taxa.

*Daniel adds: This story highlights the importance of taxonomists in conservation decisions. The Flora of North America account for this taxon lumps it into Coryphantha robustispina -- a broad, inclusive species that ranges from Arizona to Texas and includes some of northern Mexico. If one follows that interpretation, then one could question the endangered status. However, if one follows the interpretation of the US Fish & Wildlife Service and its contracted taxonomists (PDF), the narrower interpretation as Coryphantha scheeri var. robustispina yields a threatened plant taxon (more about their analysis and reviews here: Coryphantha scheeri var. robustispina).

While Eric and other colleagues were enjoying tropical sun, I went in the opposite direction for the holidays, where it was only as cold as -20C (-4F). My father took me to see this tree because of its unusual shape for an elm (seen best in the second photograph). It reminded him of some of the work of the Group of Seven, perhaps (and I'm guessing) Lismer's A September Gale or Varley's Stormy Weather.

Ulmus americana, or the American elm was often used as a street tree in the early to mid-20th century of North America. In addition to being very tolerant of air pollution and extremely hardy, its classic vase-shape is pleasing. "Was often used" because this species had little resistance to the introduction of the fungal Dutch elm disease (DED); an estimate by Alden M. Townsend, a USDA-ARS plant geneticist suggests only 1 in a hundred thousand trees before the introduction of the fungus were DED-tolerant. Upon infection, trees react by attempting to stop the spread of the fungus through blocking its xylem tissue (water-carrying cells) -- effectively, self-starvation. Needless to say, the American elm declined in numbers precipitously, with an estimate of 77 million trees dead by 1980 from the introduction of DED in 1931.

Unlike the American chestnut, though, small- to mid-sized trees of Ulmus americana can still be easily found, in part due to its prolific seed production and ability to tolerate poor soils. Young trees often reach reproductive maturity before succumbing to DED, so the species survives. However, the tall, ancient trees (to 300 years old) of previous centuries are unlikely to be seen again until resistance to DED is established, either naturally or through selective plant-breeding.

A few civic governments have put in place programs to manage (stall?) the spread of Dutch elm disease, mainly by controlling the primary vector of the disease, the elm bark beetle. Two places in North America where elms still form a significant part of the urban landscape are Washington, D.C. and Winnipeg, Manitoba.

Mary Eleanor Wilkins Freeman in Six Trees: "There was not in the whole countryside another tree which could compare with him. He was matchless. Never a stranger passed the elm but stopped, and stared, and said or thought something about it. Even dull rustics looked, and had a momentary lapse from vacuity. The tree was compelling. He insisted upon recognition of his beauty and grace. Let one try to pass him unheeding and sunken in contemplation of his own little affairs, and lo! He would force himself out of the landscape, not only upon the eyes, but the very soul..."