Coreopsis is supersize on the Channel Islands
Plants get bigger, animals smaller in isolated places
Published 4:00 am, Wednesday, October 8, 2008
Amid the seasonal scruffiness, there are signs of life in our garden. The giant coreopsis, which was looking seriously dead, has decided to leaf out. Although it's not supposed to get summer water, we had been trying to keep one of its neighbors alive, and the coreopsis received some collateral benefit. It's in a spot with the best drainage we could manage, so we hope its roots don't rot.
Longtime Chronicle readers may recall that tertiary coreopsis was the late columnist Art Hoppe's favorite fictional incurable disease. For years we thought he had copped the phrase from James Thurber's short story "The Secret Life of Walter Mitty," but a close reading shows otherwise. The patient in Mitty's heroic surgeon fantasy has obstreosis of the ductal tract, at the tertiary stage. After Mitty repairs the anesthetizer, which has been going "pocketa-pocketa-queep," with a fountain pen, a colleague warns that coreopsis is setting in. It's not tertiary coreopsis, though.
It's a plant, not a disease
Coreopsis is not a medical condition, but a genus of plants in the huge and highly successful family Asteraceae: a relative of the sunflowers, daisies, thistles, lettuces and thousands of other species. "Coreopsis" means bedbug-like, from the appearance of the seeds; tickseed is a vernacular name. Many of the 35 coreopsis species are weak-stemmed herbs with annual life cycles.
But then there's the giant coreopsis (Coreopsis gigantea), native to California's Channel Islands, Mexico's Guadalupe Island and some mainland coastal bluffs. This perennial may grow to be 6 feet tall, occasionally taller. At the top of its thick, woody stem, sprays of bright green lacy foliage emerge when the rainy season begins.
In late winter or early spring, there are clusters of yellow daisylike flowers. The overall effect is startling. "The peculiar appearance of this shrubby daisy endears it to many gardeners, some of whom liken giant coreopsis to a character from a Dr. Seuss book," write Carol Bornstein, David Fross and Bart O'Brien in "California Native Plants for the Garden."
This island giant appears to be close kin to a more conventional mainland species, the maritime coreopsis or sea dahlia (C. maritima). Crosses between the two are fertile, suggesting a recent common ancestor. It's believed that the giant coreopsis evolved on the islands, then colonized the mainland.
Why so large? Plant and animal species that originate on islands are often supersize. The phenomenon of island gigantism is best known among reptiles (the Galapagos and Aldabra tortoises, the Komodo dragon) and birds (moas and dodos), but is also well documented in plants.
Besides the coreopsis, the Channel Islands are home to a woody buckwheat and a shrubby lettuce. Herbs have evolved into larger woody plants in Hawaii, the Canary Islands and elsewhere. Remote St. Helena in the South Atlantic has a whole suite of sunflower-derived tree species. (If Napoleon Bonaparte had been a botanist, his exile might have been happier.)
Sherwin Carlquist, a student of island biology, credited the moderate climate of many islands with fostering the evolution of woody plants from nonwoody lineages. The absence of large plant-eating mammals may also have played a role. Mainland mule deer never reached the Channel Islands; the largest native herbivorous mammals are mice.
Mammals, on the other hand, tend to shrink on islands. The now-endangered island fox, once common on most of the Channel Islands, is the size of a house cat. Santa Cruz Island once supported the oxymoronic pygmy mammoth; whether its diet included giant coreopsis is unknown. Downsized elephants also inhabited islands in the Mediterranean and in Indonesia.
Other botanical wonders
The giant coreopsis is just one of the botanical wonders on the far side of the Santa Barbara Channel. The islands are the last refuge of the ironwood tree, a rose relative that once had an extensive mainland range. They're also an evolutionary cradle for new endemic species. All in all, the Channel Islands are the closest thing we have to a Galapagos.
Botanists didn't really begin to get to know this unique flora until 1874, when Albert Kellogg made a collecting foray. Kellogg, a physician from Connecticut, was one of the many Forty-Niners who never saw a gold nugget.
But California proved to have other attractions for him, and he became the state's first resident botanist. He was one of the five founders of the California Academy of Sciences in 1853. Kellogg was the first to formally describe many Channel Island plants, including the giant coreopsis and the malva rosa.
The coreopsis isn't that hard to find in local nurseries; the Dry Garden in Oakland usually stocks it. You may also be able to find it at the California Native Plant Society's annual sale at Native Here Nursery in Tilden Park. Just give it good drainage, keep it dry in summer, protect it from snails and slugs, and stand back.
California Native Plant Society East Bay Chapter Native Plant Fair: Native Here Nursery, 101 Golf Course Drive, Tilden Regional Park, Berkeley. 10 a.m.-3 p.m. Oct 18, noon-3 p.m. Oct. 19. www.ebcnps.org.
"California Native Plants for the Garden": By Carol Bornstein, David Fross and Bart O'Brien (Cachuma Press, 2005, $27.95)
Channel Islands National Park: www.nps.gov/chis
"The Song of the Dodo: Island Biogeography in an Age of Extinction": By David Quammen (Touchstone, 1997, $14.96 paperback).