Thesium 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 : 70-71

3. Thesium L. 2

Perennials, rarely annuals, without a rhizome, but often with a woody stock and sometimes producing slender stolons; stems

procumbent to erect, simple or branched. Leaves alternate, linear to lanceolate, mostly entire, 1 - to 5-veined, green or yellowish-green. Inflorescence a panicle with few-flowered branches, or a raceme. Flowers small, hermaphrodite, on short branches, with a bract and usually with 2 bracteoles. Perianth tubular to campanulate-rotate, 4- to 5-lobed, usually white inside and yellowish-green or green outside. Stamens 4 or 5. Stigma capitate. Fruit a small green nut surmounted by the persistent dry perianth.

1 Bracteoles absent

2 Stock slender, stoloniferous; persistent perianth shorter than fruit 3. ebracteatum 2 Stock thick, woody, not stoloniferous; persistent perianth

2-3 times as long as fruit 4. rostratum 1 2 bracteoles present

3 Persistent perianth equalling or longer than nut

4 Persistent perianthusually4 -lobed,2 -3times as longas nut; inflorescence usually secund 1. alpinum 4 Persistent perianth usually 5-lobed, usually ±equalling nut; inflorescence not secund 2. pyrenaicum 3 Persistentperianthmuchshorterthannut

5 Small but prominent extra lobes of the disc present between persistent perianth-lobes

6 Stoloniferous; inflorescence 2-3 cm, few-flowered, racemose; leaves usually 2 cm or less; stems mostly up to

15 cm 5. kerneranum 6 Not stoloniferous; inflorescence 5 cm or more, many-flowered, paniculate; leaves 3-5-5 cm; stems up to 25-

30 cm 6. auriculatum 5 Smallbutprominentextralobesofthediscnotpresent between persistent perianth-lobes

7 Nut reticulately veined (sometimes indistinctly so)

8 Annual; stems ascending to erect, densely covered with nuts 16. humile 8 Perennial; stems procumbent to ascending, sparsely covered with nuts

9 Perianth + infundibuliform; nut distinctly reticulately veined 15. bergeri 9 Perianth campanulate-rotate; nut indistinctly reticulately veined 17. procumbens 7 Nut only longitudinally veined

10 Stoloniferous

11 Stems robust, rigid; inflorescence usually a panicle;

leaves mostly 3-veined 12. linophyllon 11 Stems slender and rather weak; inflorescence a raceme;

leaves 1 -veined

12 Flowers subsessile; stems mostly 5-10 cm

8. parnassi 12 Flowers shortly stalked; stems mostly 10-20 cm

9. italicum 10 Not stoloniferous

13 Leaves lanceolate, distinctly 3- to 5-veined

11. bavarum 13 Leaves linear-oblong to linear, 1 -veined (rarely 3-

veined)

14 Inflorescence a raceme; branches 1 -flowered

15 Fruiting pedicel not thickened 10. dollineri 15 Fruiting pedicel thickened 18. brachyphyllum 14 Inflorescence variously paniculate; branches severalto many-flowered at least in lower part of the inflorescence

16 Bract usually 3-4 times as long as bracteoles;

perianth infundibuliform; panicle branches racemose 7. arvense 16 Bract usually ± equalling bracteoles; perianth broadly campanulate; panicle branches often paniculate

17 Stems usuallymore than 20 cm, ascending to erect,

robust, rigid; bract, bracteoles and ultimate branches not scabrid 13. divaricatum

17 Stems usually up to 15-20 cm, decumbent to longascending, slender, weak; bract, bracteoles and ultimate branches distinctly scabrid

14. humifusum