Friday, August 31, 2007
Platanthera yosemitensis, the Yosemite bog orchid... slender spike of quarter-inch-long greenish-yellow flowers... it has a smell only a true orchidophile could love (or pollinator !!!). U.S. Geological Survey botanist Alison Colwell... rediscovered it... "Some people just wrinkle
their nose, shake their head and walk away," Colwell says.
So why did this obscure wildflower generate national headlines earlier this summer? Well, it's not often that a new species of orchid is described from North America - especially from a location as well known as Yosemite
P. yosemitensis has been found and lost and found again. It was discovered in 1923 by the... plant collector George Henry Grinnell. His specimens wound up at the Rancho Santa Ana Botanic Garden in Claremont (Los Angeles
County), where Ron Coleman found them in 1993, while researching his book, "The Wild Orchids of California." Coleman drove to Yosemite that same day and found the orchid in bloom. He sent a sample of the flowers to orchid
taxonomist Charles Sheviak at the New York State Museum in Albany, who identified the plant as P. purpurascens, previously known only from the southern Rockies.
Ten years later, Colwell was preparing for a transfer to the Sierra when she got a call from fellow orchid enthusiast Dean Taylor. The orchid volume in the "Flora of North America" series had just come out, and Taylor had
spotted the anomalous-looking range map for P. purpurascens: a blob in the Four Corners country and a dot in Yosemite. "Look at that!" Taylor told Colwell. "That's not right! You have to find this orchid."
Colwell was assigned to a National Parks Inventory and Monitoring program to survey native plants. "One day my survey partner, Charlotte Coulter, and I were in a very remote wet meadow, something only bears would usually
visit. I started smelling this musky odor. The light was a certain way. I saw these stalks of tiny yellow flowers, bent down to smell them, and said, 'Oh, this is the rare orchid Dean told me to watch out for.' " She ruled out Yosemite's other bog orchids by color (one had white flowers, one had
green) and by the shape of the nectar spur: They had long, narrow spurs to accommodate long-tongued moths and butterflies. But the yellow-flowered orchid had a short, saclike spur - "scrotiform," in botanical terminology.
"It's yellow, smells bad, has a short spur. This must be it," she concluded.
Expanding the search, Colwell and her USGS colleague Peggy Moore found eight more sites for the new orchid. They sent complete specimens to Sheviak in New York and brought him out to see it... Sheviak had suspected
that the plant might be a hybrid. "But when he saw it in the field," Colwell recalls, "he said, 'Oh, no, this is completely different.' "
The species, so far known to be found only in Yosemite, was formally
described this summer in the botanical journal Madro?o, in an article co-authored by Colwell, Sheviak and Moore.
No one will say exactly where the nine locations are; the Yosemite bog orchid is in a botanical witness-protection program. Moore gives its range as "between the main stem and South Fork of the Merced River in the southern part of the park." Botanists are concerned not so much with orchid
poachers as with the impact of visitors. "Its root system is sensitive to breakage, and the ground in the bogs is soft and easily compacted," Moore says. "We're asking people not to seek it out." Lisa Acree, the park's lead botanist, says no one has reported finding it on his own so far.
Apart from its blooming time (between June and August, depending on the snowpack), little is known about the species. Its smell suggests pollination by flies or mosquitoes, but none have been caught in the act.
Genetic studies to determine its closest relatives are pending. Botanists do know that the meadows where it grows are an ancient environment that escaped the last glacial surge - about 10,000 years ago - and may have been ice-free for even longer than that. The orchid's future is uncertain: "We'd have concerns that a species of such limited distribution could decline with changes in moisture, temperature or both," Moore says.
To Colwell, the trail that led to her discovery highlights the importance of plant specimen collections. "We like to think of explorers stumbling on something new in a remote region and having this 'Aha!' moment," she says. "But it's more common for scientists to realize they have a new species on their hands when they're examining dried specimens in herbaria. Universities are getting more molecular biology oriented and not maintaining herbaria." Stanford's has been closed, its collection now with the California Academy of Sciences. "
URL : http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/08/29/HO3DRN9IP.DTL