Biennials; usually eglandular, rarely glandular; finely pubescent, sometimes canescent, trichomes dendritic. Stems erect, unbranched basally, often many-branched distally, (1.5-)2.5-12 dm. Basal leaves: petiole 1-3.5(-5.5) cm; blade pinnatifid, broadly lanceolate to oblanceolate or obovate in outline, 1.5-10(-13) cm, lateral lobes linear to oblong or narrowly lanceolate, [3-10(-15) × 1-3(-5) mm], margins entire. Cauline leaves sessile or shortly petiolate; blade smaller distally, distal lobes often narrower. Racemes considerably elongated in fruit. Fruiting pedicels erect to erect-ascending, straight, 2-8(-11) mm. Flowers: sepals erect, yellowish, oblong, 1-1.8 mm, sparsely pubescent; petals oblanceolate, 1.2-2 × 0.3-0.6 mm; median filaments 1.4-2 mm; anthers 0.3-0.4 mm. Fruits erect, (often strictly appressed to rachis), linear, slightly torulose, (4-)5-10(-15) × 0.7-1.2(-1.5) mm, (acute at both ends); valves each with distinct midvein; septum often with distinct midvein; ovules 14-22 per ovary; style 0.1-0.4 mm, glabrous. Seeds uniseriate, reddish brown, ellipsoid to narrowly oblong, 0.8-1.2 × 0.4-0.5 mm. 2n = 14, 28.
Flowering May-Sep. Alpine and subalpine areas, gravel and sand bars, scree, grassy slopes, prairies, steep rocky slopes, roadsides, disturbed sites, waste grounds, meadows, spruce-fir, pine, aspen, or sagebrush communities; 100-3500 m; Alta., B.C., Man., N.W.T., Nunavut, Ont., Que., Sask., Yukon; Alaska, Calif., Colo., Idaho, Maine, Minn., Mont., Nev., N.Mex., N.Dak., S.Dak., Utah, Wyo.
Descurainia incana is a distinctive species readily separated from the other North American taxa of the genus by having fruits and fruiting bases strictly appressed to rachises, and septums with a distinct midvein. Collections identified as such, but with fruits and pedicels not or only weakly appressed to the rachis, most likely represent hybrids between this species and others.
Duration: Perennial
Nativity: Native
Lifeform: Forb/Herb
General: Herbaceous annuals, perennials, or biennials, to 120 cm tall, stems leafy, branching above, herbage stellate-pubescent and sometimes glandular.
Leaves: An early withering basal rosette, lower leaves 3-10 cm long, pinnate, the leaflets pinnatifid and deeply incised or merely toothed in the alternate upper leaves, these short-petioled or sessile.
Flowers: Bright yellow, petals small, oblanceolate, to 3 mm long, sepals lightly pubescent, to 2 mm long, median filaments 1.5-2 mm, flowers borne in open, terminal racemes on pedicels 6-10 mm long, these becoming greatly elongated in fruit.
Fruits: Siliques 9-15 mm long, linear, short-beaked, acute at both ends, slightly constricted between the seeds (torulose), valves and septum with distinct midveins, borne on a very short or obsolete style, fruits often strictly appressed to the rachis. Seeds 4-1
Ecology: Found on gravelly soils and sandbars, in alpine and subalpine areas, grassy slopes, rocky slopes, prairies, roadsides, disturbed areas, spruce-fir, pine, aspen, and sagebrush communities, from 350-11,500 ft (106-3505 m); flowering May-August.
Distribution: Great Lakes region to Yukon, south to northern Mexico and Baja California.
Notes: Look for this species under Descurainia richardsonii in older texts. Good identifiers for this species are the seeds in a single row and the 9-15 mm siliques, these with the valves and septums with distinct midveins, borne on a very short or obsolete style.
Ethnobotany: Unknown
Etymology: Descurania is named in honor of Francois Descourain (1658-1740), a French pharmacist and botanist, while incana means grayish or hoary.
Synonyms: Numerous, see Tropicos
Editor: LCrumbacher 2011
Erect, to 1 m, ±canescent, lvs lanceolate to oblanceolate, pinnate with entire to lobed or deeply pinnatifid segments; fls 3 mm wide; mature racemes dense, the frs overlapping, the pedicels 3-6 mm, narrowly ascending; frs appressed to the rachis, linear, 5-12 נ0.7-1.3 mm; septum without veins; seeds in each locule 4-10, in one row; 2n=14, 28, 42. Throughout w. N. Amer., from nw. Can. to n. Mex., e. to Minn., Ont., and e. Que. June, July. Our pls, as here described, are var. richardsonii. (Sophia richardsoniana; S. hartwegiana; Sisymbrium incisum)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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