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Annual, biennial ( perennial herb); hairs minute, many-branched, tree-like, occasionally mixed with fewer simple hairs, club-shaped glandular papillae occasionally present.
Stem: generally branched distally.
Leaf: petioled, finely 1–3-pinnately lobed or divided, basal generally early- deciduous; cauline similar to basal, less divided distally on stem, base not lobed.
Inflorescence: elongating.
Flower: sepals erect to spreading, base not sac-like; petals obovate, yellow [± white].
Fruit: silique or silicle, dehiscent, linear, oblong, club-shaped, ellipsoid, or obovoid, not flattened, unsegmented; stigma entire.
Seed: 5–100, in 1 or 2 rows, ellipsoid to oblong, plump; wing 0.
45–47 species: Eurasia, especially North America and South America, Canary Islands. (F. Descourain, French botanist, 1658–1740) May be TOXIC to livestock. [Detling 1939 Amer Midl Naturalist 22:481–520] Taxonomically difficult, most characters highly variable.
Unabridged note: A taxonomically difficult genus due to extensive variation and continuity in most characters. The extensive interspecific hybridization, polyploidy, fertility among species, weedy tendencies of hybrids and parents, and lack of reliable morphological characters make it difficult to delimit taxa. Numerous infraspecific taxa have been recognized, but without extensive cytological, molecular, and experimental studies, recognition of narrowly defined taxa is neither practical nor useful.

Key to Descurainia

1. Fr sparsely hairy at least in youth ..... D. adenophora

1' Fr glabrous

2. Fr fusiform, obovate, club-shaped, or ellipsoid (broadly linear, widest distally)

3. Fr fusiform, obovate, or broadly ellipsoid; seeds 4–12, in 1(2) row per chamber; valve midvein obscure

4. Fr fusiform, both ends long-acute; style (0.2)0.3–0.6(0.8) mm; stem (1.3)2–10.5(13.5) dm, simple at base, branched distally ..... D. californica

4' Fr obovate, tip obtuse, acute at base; style 0.05–0.3 mm; stem (0.8)1.5–3.2(4.1) dm, branched throughout ..... D. paradisa

3' Fr club-shaped (broadly linear, widest distally); seeds 16–40, in 2 rows per chamber; valve midvein prominent ..... D. pinnata

5. Infl axis glabrous, nonglandular ..... subsp. glabra

5' Infl axis sparsely to densely hairy, glandular or not

6. Plant sparsely to densely hairy (canescent), generally glandular; sepals yellow or lavender ..... subsp. brachycarpa

6' Plant densely canescent, generally not glandular; sepals purple or rose ..... subsp. ochroleuca

2' Fr linear

7. Fr appressed; pedicel erect to erect-ascending ..... D. incana

7' Fr not appressed; pedicel widely spreading to ascending

8. Fr septum with 2- or 3-veined central band; leaves 2- or 3-pinnately lobed ..... D. sophia

8' Fr septum not veined; leaves 1-pinnately lobed

9. Fr 3–8(10) mm; petals 0.7–1.2 mm; seed 0.5–0.8 mm; plant not glandular ..... D. nelsonii

9' Fr (8)12–35 mm; petals 1.7–3 mm; seed 0.7–1.5 mm; plant glandular or not

10. Ultimate segment of cauline leaves oblong to lanceolate, dentate to incised (pinnately lobed); fruit straight or strongly incurved ..... D. incisa subsp. incisa

10' Ultimate segment of cauline leaves linear, entire; fruit straight or ± incurved ..... D. longipedicellata

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Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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