Plants of the Prairies
With the decline of prairie habitat in South Puget Sound, several plant species are now rare and threatened with extinction. Each of these species has unique characteristics – adding to the diversity of our prairies.
Golden Paintbrush (Castilleja levisecta)
This small herb with its bright electric yellow flowers and modified leaf parts are a stunning addition to the prairie’s spring flower show. Golden paintbrush occurs in Washington and British Columbia, with its largest population at Rocky Prairie Natural Area Preserve in southern Thurston County. Identification is not difficult; this is the only yellow paintbrush in South Puget Sound Prairies. The plant is a root parasite, getting some of its energy and nutrients from adjacent plants. Golden paintbrush is categorized as endangered by the State of Washington [PDF] and listed as threatened by the U.S. Fish and Wildlife Service.
White-topped Aster (Sericocarpus rigidus)
The white-topped aster is a small, nondescript sunflower. White-topped aster forms large, dense clumps of 50-200 or more shoots, spreading by rhizomes. This vegetative reproduction may complement the late flowering period of the plant, when it was historically susceptible to burning by Native Americans. Identifying the white-topped aster is easiest in the early fall, when the puffy seed heads give it away. In the South Puget Sound, the white-topped aster presence is limited to isolated habitat patches in the prairies and woodlands. White-topped aster is listed as sensitive by the State of Washington and species of concern by the U.S. Fish and Wildlife Service [PDF].
Rose Checker-Mallow (Sidalcea malviflora ssp. virgata)
The rose checker-mallow is an upright, clump-forming perennial, with rose-red flowers, related to the hibiscus. Its common name derives from its flower bloom which is roughly the size of a checker game piece, spanning up to 1 1⁄4 inches across. Each plant forms a foot wide clump of round-lobed basal leaves. Its upright stems have deeply cut leaves toped off by the mallow-flowers. It is partial to full sun. It grows two to three feet in height and blooms in the spring and summer months. As a wildflower, the species is native to high coastal meadows, and open woodlands, along roadsides, in open hills and other moist areas. In the state of Washington, the rose checkered mallow is endangered because only one known population has been found on open prairie land in Thurston County [PDF].
Small-flowered Trillium (Trillium parviflorum)
The small-flowered trillium is a showy forb found on the margins of prairies in the moist Oregon white-oak and mixed conifer hardwood forests. It needs shade and rich hummus soil. This trillium normally grows to about twelve inches tall, though some may be taller. It has dark green, large leaves with darker mottled areas. The flower sits directly on three leaves with no upper stem. Its petals stand straight up, white and narrow. Flowers fade to purple as it ages. The seed pods are plump, in the shape of hazelnuts and sit right on the junction of the three leaves. The jelly-like substance in the ripe seed pod contains a purple dye which can stain hands. The small-flowered trillium blooms around Easter. Small-flowered Trillium is a sensitive species in the State of Washington [PDF].
Torrey’s Peavine (Lathyrus torreyi)
This rare native of conifer woods grows less than a foot high and spreads its leaflets over an area the size of one’s hand. Lacking tendrils, it does not climb over, but is often dominated by its neighbors. It blooms a pale blue-lilac colored flower. It occurs in openings in conifer forests on the edges of prairies. The Torrey’s peavine was thought to be extinct in Washington until it was rediscovered on McChord Air Force Base in 1994. It is threatened in the state of Washington and a species of concern by the U.S. Fish and Wildlife service [PDF].
Are You a Botanical Sleuth?
Several other rare plants species are known historically from our prairies, but have not been seen for years. If you are a botanical sleuth, you might want to keep your eyes open for these rare plants:
Tall Agoseris (Agoseris elata) - usually occurs in meadows and open woods from low-elevation to timberline west of the Cascade Mountains.
The Common Blue-Cup (Githopsis speculariodes) - generally scattered in distribution and known from both sides of the Cascades.