ABSTRACT
Leaves opposite, at least the lower leaves.........................................2. Leaves alternate or stem without leaves........................................... 5. Plants monoecious. Anthodia bearing staminate flowers in spicate terminal inflorescences. Pistillate anthodia 1-flowered, their involucre ovoid, elongate in the upper part into a beak, with short acute spine like outgrowths in midportion on the periphery......... 24. Ambrosia. Flowers bisexual; if unisexual, flowers in a single anthodium. Antho dia with many achenes. Involucre many-leaved.............................. 3. Achenes with 2-4 hard serrate spikes................................. 28. Bidetts. Achenes with tufts of many hairs.......................................................4. Anthodia many at tip of stems and branches. Ray flowers white. Thalamus with membranous bracts. Annual plants.... 30. Galinsoga. Anthodia singly, about 5 cm in diam. Ray flowers yellow or orangecoloured. Thalamus pubescent. Perennial plants.............. 50. Arnica. All leaves in a radical rosette, floral shoot a scape, without leaves. 6. Stems with leaves (sometimes scarious, reduced). Radical leaves many or absent...................................................................................10. Anthodia with white, pink or blue ray and yellow disc flowers....7. Only ray flowers, yellow or cream-coloured.....................................8. Leaves linear, entire, achenes tufted ............................. 9. Arctogeron. Leaves spatulate or oblong ovoid-spatulate, obtuse, with dentate margin. Achenes without tuft..................................................2. Beilis. Achenes without a beak. Hairs of tuft pinnate................................. 9. Achenes beaked. Hairs of tuft simple.......... ...............88. Taraxacum. Leaves entire, venation parallel or arcuate................. 76. Scorzonera. Leaves pinnatifid...........................................................79. Leontodon. Stem with scale-like, ovoid-lanceolate brown leaves or scales......11. Stems with true leaves.......................................................................13. Anthodia with bright yellow disc and ray flowers. Radical leaves seen only after flowering, orbicular-cordate, 10-25 cm in. diam., whitish tomentose beneath, glabrous on upper surface............ 48. Tussilago.
