Thlaspi L.

74. Thlaspi L. 3

Annual or perennial herbs with sessile, ±amplexicaul cauline leaves. Hairs unbranched or absent. Inflorescence racemose, ebracteate. Sepals erect, not saccate; petals usually white or purplish, shortly clawed; stamens without appendages. Fruit an angustiseptate silicula, with or without apical notch, the valves keeled and usually winged; stigma capitate, somewhat 2-lobed. Seeds 1-8 in each loculus.

In species described as having violet anthers, the violet coloration may not appear until a late stage of dehiscence.

1 Annual, without non-flowering leaf-rosettes

2 Style long, exceeding the notch of the ripe fruit

23. macranthum 2 Style very short, included within the notch of the ripe fruit

3 Upper cauline leaves ovate, cordate-amplexicaul at the base; seeds smooth 3. perfoliatum 3 Upper cauline leaves oblong, hastate- or sagittate-amplexicaul at the base; seeds ridged or alveolate

4 Glabrous; fruit 10-15 mm in diameter, flattened, orbicular; seeds with concentric ridges 1. arvense 4 Stem hairy below; fruit 6-7 mm in diameter, obcordate, convex beneath; seeds alveolate 2. alliaceum 1 Biennial to perennial, usually with non-flowering leaf-rosettes

5 Style included within the notch of the ripe fruit, or stigma sessile

6 Plants usually more than 10 cm and sometimes reaching

50 cm; inflorescence usually elongating in fruit (lowland to alpine over much of Europe) (4-7). alpestre group 6 Dwarf plants rarely more than 10 cm, often much smaller; inflorescence scarcely elongating in fruit (mountains of S. Europe)

7 Petals 5 mm (Greece) (14-18). praecox group 7 Petals 2 mm

8 Apical notch of fruit rounded at base; stigma almost sessile

8. brevistylum 8 Apical notch acute at base; style O-3-O-5 mm 9. rivale 5 Style equalling or exceeding the notch of the ripe fruit, or notch absent

9 Ripe fruit strongly keeled but not winged; notch very narrow or absent; inflorescence scarcely elongating in fruit

10 Petals white (Spain) 26. nevadense 10 Petals purple

11 Plant caespitose; rosette-leaves spathulate, dentate; all cauline leaves alternate 25. bellidifolium 11 Plant with long or short stolons; rosette-leaves elliptical to suborbicular; lower cauline leaves opposite

24. rotundifolium 9 Ripe fruit distinctly, though sometimes very narrowly winged; notch broad or absent; inflorescence usually elongating in fruit

12 Sepals l-l-5(-2)m m; petals l-3(-4)m m; stamens about equalling or exceeding the petals; stock quite shortly branched (4-7). alpestre group 12 Sepals 2-3 mm; petals (3-5-)4-8 mm, exceeding the stamens; plants perennial; stock with short or elongated branches

13 Roots tuberous, long-tapering; flowers bright violet

(Greece) 13. bulbosum 13 Roots not tuberous; flowers white or purplish

14 Wing of fruit-valve usually c. 0-5 mm wide and never more than 1 mm wide, so forming a very shallow notch which is much exceeded by the style

(20-22). alpinum group 14 Wing of fruit-valve more than 1 mm wide and at least half as wide as the valve at its apex; notch very variable in depth and width

15 Stock with elongate stolon-like branches; plants matforming 19. montanum 15 Stock with short branches; plants ±caespitose

16 Anthers yellow (14-18). praecox group 16 At least some anthers becoming violet

17 Inflorescence almost sessile; style 0-75-1 mm

18 Flowers white; style 1 - 5 -3- 5 mm 10. graecum 18 Flowers purplish; style 3-5 mm 12. stylosum