Lepidium L.

80. Lepidium L. 2

Annual to perennial herbs, sometimes small shrubs, with usually unbranched hairs. Flowers small, in dense, terminal, ebracteate racemes. Sepals not saccate; petals white or rarely yellow (rarely absent). Stamens 2, 4 or 6. Styles short or absent. Fruit an angustiseptate silicula; valves strongly keeled, winged. Seeds usually 1, pendent from the apex of each loculus. Literature: A. Thellung, Die Gattung Lepidium (L.) R.Br.

Eine monographische Studie. Zürich. 1906. 1 Wing of the silicula connate with the lower part of the style

2 Pedicels 1-2 mm in fruit; middle and upper cauline leaves cuneate at the base 5. spinosum

2 Pedicels (2-)3-7 mm in fruit; middle and upper cauline leaves amplexicaul

3 Annual or biennial; silicula densely covered with small, scalelike vesicles; style usually not projecting beyond the apical notch of wing 1. campestre

3 Perennial; silicula with few or no vesicles; style projecting beyond the apical notch of wing

4 Silicula hairy, at least when young 4. hirtum

4 Silicula glabrous even when young 5 Pedicels glabrous in fruit 2. villarsii 5 Pedicels hairy in fruit 3. heterophyllum

1 Wing of the silicula not connate with the style

6 Silicula ±conspicuously winged and notched; style shorter than or equalling notch

7 Petals longer than sepals

8 All leaves pinnately divided or dentate 9 Upper cauline leaves dentate; silicula 3-4x2-5-3-5 mm 9. virginicum 9 Upper cauline leaves pinnately divided; silicula c. 1-5x 1-5 mm 8. cardamines 8 At least the upper cauline leaves linear and entire 10 Greenish annual; lower leaves lyrate, with toothed lobes;

silicula 5-6 x 3-5 mm 6. sativum 10 Small, glaucous shrub; all leaves linear and entire; silicula

2-2-5 x 1-5-2 mm 7. subulatum 7 Petals shorter than sepals or absent 11 Silicula 2-3 x 1-2-3 mm 12 Style longer than notch; pedicels erecto-patent 16. schinzii 12 Style shorter than notch; pedicels patent

13 Stem covered with papillae 14. divaricatum

13 Stem glabrous or with a few smooth hairs

14 Stem often with a few unbranched hairs; upper cauline leaves linear, entire; silicula deeply notched

13. ruderale

14 Stem glabrous; upper cauline leaves oblanceolatespathulate; silicula with entire or rarely slightly emarginate apex 15. pinnatifldum 11 Silicula 2-5-4 x 2-25-3 mm 15 Stem hairy; upper cauline leaves pinnate 10. bonariense 15 Stem papillose; upper cauline leaves entire or dentate

16 Upper cauline leaves linear-lanceolate, the margins usually with remote teeth, lateral veins visible

11. densiflorum

16 Upper cauline leaves linear, entire, 1-veined

12. neglectum 6 Silicula usually not winged, entire (or if slightly notched, then always with an exserted style longer than notch) 17 Petals yellow; leaves strongly dimorphic, the lower 2- to

3-pinnatifid, the upper suborbicular, entire, with broad,

rounded lobes completely enclosing the stem and overlapping 17. perfoliatum 17 Petals white; leaves not strongly dimorphic; the upper leaves without broad, rounded lobes enclosing the stem 18 Cauline leaves either linear to linear-spathulate or pinnatisect, with narrow lobes 19 Basal leaves linear to linear-lanceolate, pinnatisect, with narrow lobes; petals about twice as long as sepals;

silicula c. 2 x 1-1-5 mm 20. lyratum 19 Basal leaves oblanceolate to oblong, dentate or pinnately lobed with broad lobes; petals equalling or up to 1 |

times as long as sepals; silicula 2-5^4 x 1-5-3 mm

21. graminifolium 18 Cauline leaves ovate, elliptical or lanceolate, entire 20 Stem papillose; ripe silicula distinctly reticulatealveolate 18. cartilagineum 20 Stem glabrous; ripe silicula smooth or faintly reticulate

19. latifolium