Thelypodium howellii

Howell's thelypody (Thelypodium howellii), is a rare plant of the Western U.S. It is endemic to a relatively small area on the borders of three western States: Oregon, Nevada, and California.

Technical Description

Plant biennial, more or less hispid-pubescent or sparsely to rather heavily hirsute near the base, otherwise glabrous, somewhat glaucous. Stems slender, erect, usually branched at the base, sometimes sparingly branched above, 30–70 cm tall. Leaves primarily basal in a rosette. Basal leaves several, more or less rosulate, not or sparsely haired, oblanceolate, obtuse, lyrately lobed to occasionally entire, 2–4 (10) cm long; petiole short. Cauline leaves rather numerous, glabrous, glaucous, entire, narrowly oblong to linear–lanceolate, acute, erect and usually appressed, sagittate at the base and often somewhat clasping, sessile, 1½–3 (10) cm. Racemes elongate, lax, racemose, not at all corymbose. Flowers relatively distant; pedicels stout, ascending, 2–5 mm; sepals oblong, nearly erect, usually purplish or greenish-white, lateral, somewhat saccate at the base, scarious–margined, 4–9 (usu. 7) mm; petals pale blue, lavender, or purple, narrowly spatulate (spoon-shaped), crispate at base, twice as long as the sepals (8–20 mm); stamens slightly longer than the sepals, with paired filaments partly to completely fused, about equaling the sepals, and 2–2½ mm anthers; style ½–1½ mm; style long; stigma small, entire, not lobed; septum uniformly coloured. Pods cylindric siliques, somewhat curved inward, ascending to erect, somewhat torulose, 1½–4½ cm long, about 1 mm broad; stipe a little less than ½ mm. Seeds thick, plump, brown.

Distribution, Habitat, and Ecology

This plant is endemic to a small area stretching from north-eastern Oregon to north-eastern California. It lives in alkaline or adobe meadows and seeps, river valleys and moist plains in Great Basin sagebrush scrub. The fire ecology of this plant is not known at present.

Conservation Status and Threats

U.S. Forest Service Pacific Southwest Region Sensitive Species.

California Native Plant Society List 1B.2.

NatureServe California State Rank: S2.2; Global Rank: G2

The threats facing Howell's thelypody are not known at present.

Field Identification

Howell's thelypody flowers from May to July. Var. spectabilis, known only from Malheur Co., Oregon, is larger than var. howellii, has larger, more strongly purple flowers, and is a federally listed species.


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