Asters are annual, biennial, or perennial herbs with alternate leaves and solitary to more often numerous, hemispheric to top-shaped flowerheads. The flowerheads usually have rays of varying shades of blue, purple, or pink to white. In a few species the female flowers are rayless, and in a few others the female flowers are lacking. The involucral bracts are herb-like throughout (the outer sometimes leaf-like and longer than the inner), or more often paper-textured below, or sometimes paper-textured throughout, often strongly partly overlapping. The receptacle is flat or a little convex, and naked. The disk flowers are more or less numerous, yellow (sometimes pale) or often reddish-purple. The anthers are entire or minutely arrow-shaped at the base. The style branches are flattened, with inward-facing marginal stigma-bearing lines and lanceolate or narrower, pointed, minutely hairy appendages generally over 0.5 mm long. The achenes are mostly several-nerved, rarely only 2-nerved. The pappus consists of more or less numerous hair-like bristles. The genus consists of about 250 species worldwide, mostly in N. America, but extending into S. America, and also widely distributed in Eurasia.
Guide to Identify Presented Species of Genus Aster
FLOWERS WHITE. INVOLUCRAL BRACTS SPINE-TIPPED
A. ericoides – Heath Aster Perennial 30-100 cm tall, often clustered. Open, wet or dry places in the valleys.
Flowerheads densely clustered on branches, with 15-25 white rays 3-8 mm long.
Leaves numerous, firm, linear, spine-tipped, 4-7 cm long and 4-5 mm wide.
INVOLUCRAL BRACTS GLANDULAR
A. conspicuus – Showy Aster Stout, unbranched perennial, 30-100 cm tall. Open woods, foothills to montane.
Flowerheads blue-violet, with 12-35 rays, many in clusters. Involucre glandular.
Leaves alternate, firm, sharp-toothed, elliptic, 6-15 cm long and 2-6 cm wide.
