Pacific trillium

Description

Trillium ovatum, the Pacific trillium, also known as the western wakerobin, western white trillium, or western trillium, is a species of flowering plant in the family Melanthiaceae. It is found in western North America, from southern British Columbia and the tip of southwestern Alberta to central California, east to Idaho and western Montana. There is an isolated population in northern Colorado and southern Wyoming. T. ovatum is the most widespread and abundant trillium in western North America. It is the only pedicellate-flowered Trillium species found within its range. The type specimen for this species was gathered by Meriwether Lewis in 1806 along the Columbia River during the return trip of the Lewis and Clark Expedition. The most widespread of the western North American trilliums, Trillium ovatum varies greatly within its range. Despite this, T. ovatum closely resembles the eastern T. grandiflorum. Apart from geographic location, the two species are not easily distinguished. T. ovatum is a perennial herbaceous plant that spreads by means of underground rhizomes. At maturity, each plant has one or two flowering scapes, each 20 to 50 cm (8 to 19.5 in) in length. The specific epithet ovatum means “egg-shaped,” which refers to the petals, not the leaves. The latter are generally ovate-rhombic, 7 to 12 cm (3 to 5 in) long by 5 to 20 cm (2 to 8 in) wide. The flower sits on a pedicel 2 to 6 cm (1 to 2.5 in) in length. The sepals are 15 to 50 mm (0.59 to 1.97 in) long and 6 to 20 mm (0.24 to 0.79 in) wide, while the petals are 15 to 70 mm (0.59 to 2.76 in) long and 10 to 40 mm (0.39 to 1.57 in) wide. Typically the flower opens white and becomes pink with age, but in the Smith River Canyon area of northern California and southern Oregon, the petals become almost barn-red. In addition to Trillium ovatum Pursh, the following infraspecific taxa are accepted by the World Checklist of Selected Plant Families: Trillium ovatum var. oettingeri (Munz & Thorne) Case Trillium ovatum var. ovatum The variety T. o. var. oettingeri is endemic to the Salmon Mountains of northwestern California and hence Oettinger's trillium is known as the Salmon Mountains wakerobin. Unlike the nominate variety T. o. var. ovatum, the variety oettingeri has leaves with short petioles and linear flower petals.