The Jepson Herbarium
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Annual to perennial herb ( shrub); hairs 0 or simple.
Leaf: basal rosetted or not, petioled, entire, dentate, to 1–3-pinnately lobed; cauline short-petioled to sessile, base occasionally lobed to clasping.
Inflorescence: elongated or congested.
Flower: sepals erect or spreading, oblong to ovate, base not sac-like; petals linear to obovate, white or yellow (pink or purple), occasionally reduced or 0; stamens 2, 4, or 6.
Fruit: silicle, generally dehiscent, oblong to ovate, obcordate, or round (spectacle-shaped), flat perpendicular to septum (inflated), unsegmented.
Seed: 2(4), gelatinous when wet; wing narrow or 0.
220 species: all continents except Antarctica. (Greek: little scale, from fruit) [Al-Shehbaz et al. 2002 Novon 12:5–11]
Unabridged references: [Hitchcock 1936 Madroño 3:265–300]

Key to Lepidium

1. Middle or distal cauline leaf bases lobed to sagittate or clasping

2. Most distal cauline leaves deeply cordate-clasping; basal leaves 2–3-pinnately lobed or divided; flowers pale yellow; seeds narrowly winged ..... L. perfoliatum

2' Most distal cauline leaf bases lobed or sagittate; basal leaves entire (divided or 1–2-pinnately lobed); petals white; seeds wingless

3. Stamens 2; petals 0 or to 0.7 mm; basal leaves 1–2-pinnately lobed; style to 0.1 mm ..... L. oblongum (2)

3' Stamens 6; petals 1.5–5 mm; basal leaves dentate or entire (divided); style >= 0.2 mm

4. Plants not rhizomatous; fruit dehiscent, tip wide-winged, notched; inflorescence elongated

5. Annual; fruit valves papillate; style 0.2–0.5(0.7) mm, included or ± exserted beyond notch ..... L. campestre

5' Perennial; fruit valves generally not papillate; style (0.6)1–1.5 mm, well-exserted beyond notch ..... L. heterophyllum

4' Plants rhizomatous; fruit indehiscent, tip wingless, not notched; inflorescence generally panicles

6. Fr flat, cordate to ± reniform; valves net-veined ..... L. draba

6' Fr inflated, spheric to obovoid, generally not net-veined

7. Fr hairy, spheric, (2)3–4.4(5) mm wide; style 0.5–1.5 mm ..... L. appelianum

7' Fr glabrous, obovoid, (3.5)4–6.2(7) mm wide; style (0.8)1.2–2(2.3) mm ..... L. chalepense

1' All cauline leaf bases not lobed, sagittate, or clasping

8. Fr indehiscent, valve walls thick, ridged or tubercled

9. Fr reniform to ovate-cordate, 2.3–3.4 mm, ridged, tip not notched; stamens 6 ..... L. coronopus

9' Fr spectacle-shaped, 1.3–1.7 mm, not ridged, tip notched; stamens 2 ..... L. didymum

8' Fr dehiscent, valve walls thin or thick, not ridged or tubercled

10. Biennial to subshrub, with woody caudex or base

11. Basal leaves entire or serrate ..... L. latifolium

11' Basal leaves pinnately lobed or 0

12. Plant glabrous; basal leaves 0; fruit 4.2–7(8) mm wide ..... L. fremontii

12' Plant puberulent at least on pedicels or rachis; basal leaves generally present; fruit (1.5)1.8–3.6(4) mm wide ..... L. montanum (2)

10' Annual or biennial, not woody

13. Stamens 2

14. Fr prominently net-veined; sepals persistent ..... L. strictum

14' Fr not veined (weakly veined); sepals deciduous

15. Pedicel strongly flattened; fruit valves stiff hairy or bristly at least on margin ..... L. lasiocarpum subsp. lasiocarpum

15' Pedicel cylindric or ± flattened; fruit valves glabrous or puberulent

16. Fr elliptic ..... L. ramosissimum

16' Fr round to obovate

17. Plant stiff hairy; mid-cauline leaves pinnately lobed ..... L. oblongum (2)

17' Plant puberulent or glabrous; mid-cauline leaves entire or dentate to serrate

18. Fr obovate; rachis hairs 0 or straight, generally club-shaped; petals 0 or 0.3–0.9 mm ..... L. densiflorum

18' Fr ± round; rachis hairs curved; petals 1–2.5 mm ..... L. virginicum

19. Fr glabrous or puberulent; pedicel flattened at least below tip, (0.2)0.3–0.4 mm wide ..... subsp. menziesii

19' Fr glabrous; pedicel cylindric, 0.15–0.2 mm wide ..... subsp. virginicum

13' Stamens 4 or 6

20. Stamens 6; style (0.1)0.2–1.6 mm, generally exserted from fruit notch

21. Fls yellow

22. Pedicel glabrous, (2.7)3–4.4(5) mm; inflorescence rachis glabrous; fruit tip winged; notch 0.2–0.6 mm ..... L. flavum

22' Pedicel hairy adaxially, 5–15 mm; inflorescence rachis hairy or glabrous; fruit tip wingless, notch 0 (0.1 mm) ..... L. jaredii

21' Fls white

23. Biennial or perennial herb; rachis puberulent, hairs straight or curved ..... L. montanum (2)

23' Annual; rachis hairs long, straight, mixed with shorter club-shaped ..... L. thurberi

20' Stamens 4; style 0 (0.1 mm), included in fruit notch

24. Pedicel cylindric or ± flattened

25. Fr 2.4–3.6 mm, tip winged, notch 0.3–0.8 mm; petals 0 ..... L. oxycarpum

25' Fr 1.8–2 mm, tip wingless, notch to 0.1 mm; petals 0.4–0.6 mm ..... L. pinnatifidum

24' Pedicel strongly flattened

26. Sepals persistent; fruit valve hairs stiff, spreading, mixed with much smaller hairs; petals hairy abaxially ..... L. latipes

26' Sepals not persistent; fruit valves glabrous or sparsely uniformly puberulent; petals 0 or glabrous abaxially

27. Fr valves not or obscurely veined; pedicel not appressed ..... L. nitidum

27' Fr valves strongly net-veined; pedicel appressed

28. Fr (3)4–6 mm, 2.5–3.5 mm wide, notch (0.8)1–2 mm, V-shaped; pedicel (2)3–4.2 mm ..... L. acutidens

28' Fr 2.5–3.5 mm, 2–2.8 mm wide, notch 0.5–0.7(0.8) mm, U-shaped; pedicel (1.6)1.9–2.5(3) mm ..... L. dictyotum

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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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