giant purple wakerobin

Trillium kurabayashii is a perennial herbaceous plant that persists by means of an underground rhizome. Like all trilliums, it has a whorl of three bracts (leaves) and a single trimerous flower with 3 sepals, 3 petals, two whorls of 3 stamens each, and 3 carpels fused into a single ovary with 3 stigmas. Since its flower has no stalk, it belongs to subgenus Sessilia, the sessile-flowered trilliums. Scape erect, 28–44 cm (11–17 in) long, usually 2.3–2.5 times as long as the bracts. Bracts sessile, ovate or widely ovate, 11–18 cm (4.3–7.1 in) long, dark green, with tips generally slightly acuminate. Sepals lanceolate, 42–70 mm (1.7–2.8 in) long, diverging, greenish or basally purple. Petals oblanceolate, 65–105 mm (2.6–4.1 in) long, usually 3.3–4.6 times longer than wide, erect, dark purple (variously referred to as maroon-red, red-purple, purple-red, or lurid purple), underside usually duller than the top. Stamens erect, 16–25 mm (0.63–0.98 in) long; filaments short, dark purple; anther sacs introrse, 14–21 mm (0.55–0.83 in) long, with yellow pollen; connectives prolonged up to 0.5 mm. Carpels approximately 4/5 as tall or equal to the stamens; ovary ovoid, 9–13 mm (0.35–0.51 in) tall, dark purple, a rounded hexagon in cross section; stigmas coarsely subulate, 6–8 mm (0.24–0.31 in) long, erect, dark purple. …

There are two small disjunct populations of Trillium kurabayashii in the western United States. One population extends along the western slope of the Klamath Mountains from Curry County in extreme southwestern Oregon to Humboldt County in northwestern California. (The type specimen was found at the edge of a logged redwood forest in the town of Klamath in Del Norte County, California.) The other population occurs in the western foothills of the Sierra Nevada, in Placer, Nevada, Yuba, and Butte counties in northern California. Outside of its native range, citizen scientists have observed T. kurabayashii in a handful of counties in California and Oregon. The native range of Trillium kurabayashii overlaps with that of T. angustipetalum and T. albidum. T. kurabayashii is found along streams at the edges of coastal redwood forests; in rich, moist conifer-hardwood forests; and at the higher elevations, both in forests and in open grassy meadows with scattered oak trees. It grows at elevations of 30–150 m (98–492 ft) along the coast and 300–1,000 m (980–3,280 ft) in the Sierra Nevada.

On the West Coast, Trillium kurabayashii flowers from late March to mid-April. Flowering is somewhat later in the Sierra Nevada, from early April to early May. It is winter-hardy in central Michigan gardens, but it emerges so early that it gets damaged by frosts and therefore never thrives in that region.

A garden plant known in the nursery trade as Trillium sessile var. rubrum was widely bought and sold in the 1950s and 60s. It had sessile flowers with large, dark red, erect petals over strongly mottled, sessile leaves. The availability of this plant was largely due to the efforts of a man named Gilman Keasey of Corvallis, Oregon who grew the plants from seed in great quantities. By 1968 his annual crop of flowering size plants had reached about 15,000. Keasey collected his original three plants in northwestern California in 1947, suggesting that the species was in fact Trillium kurabayashii, the only species of sessile-flowered trillium now known to occur in that region.