Inula L.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1976, Flora Europaea. Volume 4. Plantaginaceae to Compositae (and Rubiaceae), Cambridge University Press : 133-134

31. Inula L. 3

Perennial, rarely biennial herbs or small shrubs. Leaves simple, alternate. Capitula solitary or in a corymbose or paniculate inflorescence. Involucral bracts imbricate, in many rows. Recep­ tacle flat or slightly convex, without scąles. Florets yellow, the outer ligulate, female, the ligule often very short. Tubular florets hermaphrodite. Achenes angled, not abruptly contracted below the pappus. Pappus-hairs simple, free.

Literature: G. Beck, Denkschr. Akad. Wiss. Math.-Nat. Kl. (Wien) 44: 283-339 (1882). K. H. Rechinger fil., Österr. Bot. Zeitschr. 87: 81-100 (1938).

Putative hybrids between 2-7 have been recorded from areas where any two of these species grow together. In many cases the morphological evidence strongly supports the view that these plants are of hybrid origin, but in others they appear to be variants of one or other of the alleged parents.

1 Outer involucral bracts 4 mm or more wide, ovate; ligules 30-40 mm; achenes 3-5 mm 1. helenium

1 Outer involucral bracts less than 4 mm wide, linear or lanceo­ late, rarely triangular to ovate; ligules less than 30 mm; achenes 1 -3 mm

3 Middle and upper cauline leaves cuneate at base, not amplexicaul or decurrent 4 Pappus 3-4 times as long as the achene, with c. 30 setae; leaves puberulent to thinly grey-tomentose beneath 16. conyza 4 Pappus about twice as long as the achene, with 10-15 setae; leaves densely white-tomentose or -lanate beneath (13-15). candida group 3 Middle and upper cauline leaves amplexicaul or decurrent, usually ± cordate at base 5 Cauline leaves decurrent 6 Stem and leaves glabrous or with sparse, long, patent hairs 18. bifrons 6 Stem and leaves densely villous with appressed hairs 17. thapsoides 5 Cauline leaves amplexicaul, but not decurrent 7 Achenes glabrous; capitula 7-11 mm in diameter 3. germanica 7 Achenes hairy; capitula at least 15 mm in diameter 9. caspica 2 Ligules 12 mm or more, more than 1| times as long as the involucre 8 Leaves with 3-7 parallel veins 7. ensifolia 8 Leaves pinnately veined or the veins obscure 9 Small shrub; leaves not more than 5(-8) mm wide, fleshy, with obscure lateral veins 19. crithmoides 9 Herbs; leaves usually more than 5 mm wide, not fleshy, with distinct lateral veins 10 Upper surface of leaves with prominent reticulate venation 11 Outer involucral bracts about as long as inner, all linear to lanceolate; lower surface of leaves and involucral bracts ± densely hairy 6. hirta 11 Outer involucral bracts ovate to oblong-lanceolate, ± spathulate at apex, shorter than inner, the inner linear; lower surface of leaves and involucral bracts glabrous or sparsely hairy 12 Upper cauline leaves cordate at base and distinctly amplexicaul 4. salicina 12 Upper cauline leaves cuneate at base, not amplexicaul 5. spiraeifolia 10 Upper surface of leaves without prominent reticulate venation 13 Cauline leaves cuneate at base, not amplexicaul 14 Stem 30-60 cm; outer involucral bracts ovate-lanceolate, with recurved apex 2. Helvetica 14 Stem 10-25(-35) cm; outer involucral bracts lanceolate, with appressed apex 12. montana 13 Cauline leaves ± cordate at base and amplexicaul 15 Outer involucral bracts patent or deflexed 16 Outer involucral bracts 0-5-0- 8 mm wide, longer than inner; ligules 15-25 mm 8. britannica 16 Outer involucral bracts 1 -1-3 mm wide, shorter than inner; ligules 9-14 mm 9. caspica 15 Outer involucral bracts usually erect 17 Outer involucral bracts 5-7 mm, distinctly shorter than inner; capitula 25-30 mm in diameter 10. oculus-christi 17 Outer involucral bracts c. 10 mm, almost as long as inner; capitula 50-80 mm in diameter 11. helenioides