The landscape of Southern Oregon’s Illinois Valley is dry and sparse, but it nurtures some of the most unique and diverse plant communities in the Northwest.
The Rough and Ready Botanical Wayside, a few minutes from the town of Cave Junction, doesn’t look like much from a distance. The only trees that grow along rocky Rough and Ready Creek are miniature oaks and hardy Jeffrey pines.
“The oaks here are shorter than I am,’ says Suzanne Vautier, a local naturalist who leads hikes for the Oregon Native Plant Society. “Yet they are quite old.”
Want to go where we did for this report? Here are some tips.
Want to learn more about endemic species in the Siskiyous? On June 9th, the Siskiyou Field Institute is offering a course on the Geobotany of the Siskiyou Mountains.
Most plants cannot survive at all in the strange soil that stunts the trees at this botanical wayside.
Vautier says the Klamath and Siskiyou mountains in Southern Oregon and Northern California are among the few places in the world with large areas of soil composed of eroded serpentine and peridotite.
Serpentine soils tend to have little calcium, a nutrient most plants need, and are heavy in nickel, chromium, selenium, and other toxic metals.
So the plants that grow here have adapted and many are found nowhere else in the world. Vautier says the environment favors small, slow growing species. Vautier points out a delicate flower with hairy leaves, Waldo’s rock cress, one of many endemic species.
Her favorite, she says, is Douglas’ monkey flower, a pink flower just an inch or two high, with petals like Mickey Mouse ears.
Many of the endemic plants at the wayside spend most of their lifecycle as bulbs in the soil and appear only for a week or two in the spring to bloom and reproduce.
Jeffrey pines are well suited to the environment, Vautier says, because they shed their needles infrequently, conserving energy.
And then there are the cobra lilies.
“Eating insects. That’s a pretty exotic adaptation for living in low nutrient soils,” says Dr. Frank Lang, a professor emeritus of biology at Southern Oregon University.
At the Eight Dollar Mountain Botanical Area, thousands of insect-eating cobra lilies, darlingtonia californica, grow in fens, where water seeps up out of the mountain. Lang says that the carnivorous darlingtonia lure beetles and wasps down a long tube. At the bottom, a bacterial brew breaks down the bugs so the plant can absorb the nutrients. Frank says the darlingtonia are common at serpentine fens in Southern Oregon.
The metal-rich serpentine soils that form the base of these plant communities also have an unusual life story. Serpentine and peridotite deposits are rare because they start their life as metal-rich igneous rock in the earth’s mantle, called ultramafic rock. Serpentines can form when ultramafic, or mantle, rock spreads out from mountain ranges underneath the middle of the ocean.
Charles Lane, a geology professor at southern Oregon University, says most of that oceanic rock subducts and re-melts when it hits a continental plate. But occasionally, the ultramafic rock gets scraped off onto the edge of the continent, a process called obduction. And in the process, it can metamorphose into serpentines.
“With the formation of the Klamath Mountains, we had a pretty fair mass of this stuff obducted,“ says Lane.
While serpentine areas are home to the greatest diversity of plant species, spectacular and rare wildflowers bloom on Siskiyou slopes with more normal soils too. Endangered Gentner’s fritillary, a red lily, bloom in the Jacksonville Woodlands in April. And after the spring rains, dwarf wooly meadowfoam, another endangered endemic flower, bloom alongside pools of water that form briefly on Table Rocks, a pair of volcanic buttes.
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