The World Flora Online

Herbes'vivaces à racines tubereuses ou à rhizomes ligneux, rarement herbes annuelles ou petits arbustes.'Feuilles'alternes, simples, lancéolées à ovales, entières ou rarement dentées.'Capitules'hétérogames, radiés, oligo- à multiflores, solitaires ou groupés en cymes. Involucre 3-4(-5)-sérié, imbriqué, à bractées involucrales externes plus courtes que les internes.'Fleurs'périphériques femelles, ligulées, bleues, mauves, roses à blanches, parfois pourvues des staminodes.'Fleurs'centrales hermaphrodites, tubuleuses, jaunes, à corolle ± campanulée ou infundibuliforme dans la partie supérieure et 5-lobée au sommet. Anthères linéaires, obtuses à la base, à appendice apical lancéolé. Style cylindrique ou linéaire, bifide au sommet, à branches linéaires.'Akènes ellipsoïdaux ou obovoïdes, légèrement comprimés, bruns à noirâtres, ± pubescents et glandulaires; pappus 2-sérié, à série interne sétacé, à série externe plus courte et généralement légèrement squamiforme; soies barbelées (surtout celles de la série interne).\n\t\t\t\tLectotype:'Aster amellus L.\n\t\t\t\tGenre très vaste groupant quelques centaines d'espèces réparties en Amérique, en Asie et en Europe; en Afrique 17 espèces, la plupart en Afrique du Sud-Est. Pour la flore d'Afrique centrale: une espèce.

Heads generally radiate, the rays pistillate and fertile, anthocyanic or white, in a few spp. reduced and inconspicuous or even wanting, the cor of the pistillate fls then a mere slender tube; invol bracts in 2 or more series, equal or more often imbricate, usually ± herbaceous at the tip and chartaceous below, sometimes herbaceous or chartaceous throughout; receptacle naked, flat or a little convex; disk-fls perfect and fertile, red or purple to yellow; style-branches flattened, with mostly narrow and acute or acuminate, externally short-hairy appendage; achenes several-nerved; pappus of numerous capillary bristles, sometimes with an additional short outer series; perennial (seldom annual) herbs, most spp. fibrous-rooted, with simple, alternate, entire or variously toothed lvs and solitary to more often several or numerous, hemispheric to subcylindric heads. (Brachyactis, Doellingeria, Ionactis, Sericocarpus) 175+, mainly N. Amer. Our spp. bloom in mid- or late summer and fall. Hybrids abound; some of the more notable ones are here formally treated. Some of the species with chromosome numbers based on x=8 (especially in the Heterophylli) tend to have additional B-chromosomes, and have often been reported to have numbers based on 9. The disk-cors characteristically consist of a slender (often short) basal tube and a more swollen limb; the lobes are part of the limb. The terms lvs basally disposed and lvs chiefly cauline are here used as explained under Solidago.

Achenes ellipsoid or obovoid, slightly compressed, pubescent and glandular; pappus of many usually unequal bristles, rarely double with an outer row of scale-like bristles. Capitula heterogamous, usually radiate, few–many-flowered, solitary or in corymbs; phyllaries 3–4(–5)-seriate, imbricate, the outer shorter than the inner Ray florets female, usually 1-seriate, sometimes with staminodes; central flowers hermaphrodite, tubular, 5-lobed, anthers linear, obtuse at the base, with a lanceolate appendage at the apex, style bifid with linear branches Leaves alternate, entire or dentate-pinnatifid Herbs with tuberous roots or woody rhizomes, rarely annual herbs or small shrubs Capitula heterogamous, usually radiate, few–many-flowered, solitary or in corymbs; phyllaries 3–4(–5)-seriate, imbricate, the outer shorter than the inner Ray florets female, usually 1-seriate, sometimes with staminodes; central flowers hermaphrodite, tubular, 5-lobed, anthers linear, obtuse at the base, with a lanceolate appendage at the apex, style bifid with linear branches Leaves alternate, entire or dentate-pinnatifid Herbs with tuberous roots or woody rhizomes, rarely annual herbs or small shrubs