Sisymbrium L.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1964, Flora Europaea - Volume 1. Lycopodiaceae to Platanaceae, Cambridge University Press : 264

1. Sisymbrium L. 1

Annual or perennial herbs; glabrous or hairs unbranched. Leaves entire to pinnatisect. Sepals not saccate at base; petals yellow, rarely white, entire. Fruit a siliqua; valves usually 3- veined; style distinct; stigma more or less 2-lobed. Seeds small (not more than 2-5 mm). Many of the widespread lowland species occur as weeds, and, as such, are often of uncertain status in many parts of Europe. Literature: O. E. Schulz in Engler, Pflanzenreich 86 (IV. 105):

46-157 (1924). 1 Inflorescence bracteate, at least in the lower part

2 Flowers white; valves of the siliqua with a distinct median vein and reticulate lateral veins 1. supinum 2 Flowers pale yellow; valves of the siliqua 3-veined

3 Petals 2-5-3-5 mm; style almost as thick as siliqua 16. runcinatum

3 Petals 1-5-2-5 mm; style distinctly thinner than siliqua

4 Pedicels 0-5-1 mm in fruit; siliqua recurved; style 0-5—1 mm

14. polyceratium 4 Pedicels 2-3 mm in fruit; siliqua ±straight; style 1-2 mm

15. confertum 1 Inflorescence ebracteate

5 Siliqua not more than 20 mm, closely appressed to the stem

6 Siliqua (8-)10-20 mm, straight, conical-cylindrical; petals

2-4 mm 18. officinale 6 Siliqua 7-10 mm, curved or twisted, strongly compressed at the apex; petals c. 1-5 mm 19. matritense 5 Siliqua usually more than 20 mm, not closely appressed to the stem

7 Lower leaves ovate, entire or dentate

8 Annual; petals less than 3 mm, not exceeding the sepals

17. erysimoides 8 Biennial or perennial; petals more than 3 mm, exceeding the sepals

9 Seeds 2-3 mm; lower pedicels 5-10 mm in fruit; petals 4-5-10 mm 2. strictissimum 9 Seeds 1-1-5 mm; lower pedicels 3-6 mm in fruit; petals

3-5-5 mm 8. austriacum 7 At least the lower leaves deeply lobed or divided

10 Petals less than 3 mm, shorter than or only slightly exceeding the sepals; anthers c. 0-5 mm

11 Pedicels 3-6 mm in flower, up to 20 mm in fruit and much thinner than the siliqua 3. irio 11 Pedicels 1-2 mm in flower, up to 5 mm in fruit and almost as thick as the siliqua

12 Lower leaves lyrate-pinnatifid, the lateral lobes obovate to lanceolate; stamens c. 3 mm, longer than the petals

17. erysimoides 12 Lower leaves sinuate-pinnatifid, the lateral lobes

±triangular; stamens c. 1-5 mm, shorter than the petals 14. polyceratium 10 Petals 3 mm or more, distinctly exceeding the sepals;

anthers (O-7-)l-3 mm

13 Pedicel about as thick as siliqua, usually at least 0-7 mm

in diameter at the base

14 Ovules not more than 30 in each loculus; siliqua rarely more than 60 mm 8. austriacum 14 Ovules 40-60 in each loculus; siliqua 50-100(-180) mm

15 Uppermost leaves ± sessile, pinnatisect, with the terminal lobe linear; outer sepals horned 12. altissimum 15 Uppermost leaves shortly petiolate, entire or hastate,

with the terminal lobe oblong or lanceolate; outer sepals not horned 13. orientale 13 Pedicel thinner than siliqua, rarely more than 0-5 mm in diameter at the base

16 Inflorescence very contracted, the young siliquae distinctly overtopping the flowers and buds; anthers

c. 0-7 mm 3. irio 16 Inflorescence elongate, the young siliquae not or scarcely overtopping the flowers; anthers 1-2 mm 17 Siliqua less than 15 mm, usually strongly contorted

8. austriacum 17 Siliqua more than 15 mm, straight or only slightly contorted

18 Septum of the siliqua white, opaque; stem glabrous or with short upwardly curving hairs; seeds 1-1-5 mm

19 Valves of siliqua with slender veins; septum not or only slightly foveolate; petals usually less than

6-5 mm 8. austriacum

19 Valves of siliqua with prominent, usually very thick veins; septum foveolate; petals more than 6-5 mm

(9-11). crassifolium group

18 Septum of the siliqua more or less hyaline; stem glabrous or hispid

20 Seeds 0-7-1 mm; sepals 2-4 mm; petals 4-7 mm

21 Stem and leaves pubescent, at least in the lower part; basal leaves not distinctly larger than the cauline, often dead at the time of flowering 4. loeselii

21 Stem and leaves glabrous or glabrescent; basal leaves 15-35 cm, persistent, much larger than the cauline 5. assoanum

20 Seeds 1-1-5 mm; sepals 3-5-6 mm; petals 6-10 mm

22 Lower leaves triangular-hastate with prominent basal lobes; siliqua 1-1-2 mm in diameter, the valves with weak lateral veins 7. volgense

22 Lower leaves deeply pinnatisect with c. 4 pairs of lobes; siliqua 0-7-1 mm in diameter, the valves

± distinctly 3-veined 6. polymorphum