Trees, shrubs, herbs, or woody or herbaceous climbers; leaves alternate or opposite, simple or compound, entire or variously lobed, toothed, parted or sinuate; stipules absent; flowers borne in heads (capitula) subtended by an involucre of seriate free or connate bracts; sometimes capitula of only one flower; receptacle convex or flat, sometimes concave; receptacular bracts usually present; flowers {florets) of 2 kinds, one or both kinds present in the capitulum, ray-florets ligulate, i.e. the corolla split along one side, more or less flattened, often enlarged and specially colored, these generally peripheral; disc-florets tubular, corolla merely toothed or lobed, usually regular, these generally central; florets perfect or unisexual, sometimes dioecious, the disc- and ray-florets often differing sexually; calyx present as a pappus of filaments or bristles; corolla 4-5-lobed, valvate, sometimes bilabiate; stamens 5 (rarely 4), inserted on the corolla, with free filaments, but the anthers laterally connate and forming a tube surrounding the style (or very rarely free), 2-celled, longitudinally dehiscent; ovary inferior, 1-celled, with 1 erect ovule; style bifid and usually with pilose stigmatic regions; fruit an achene, 1-seeded, often capped by the plumose pappus; seed without endosperm.--A very large World-wide family of about 900 genera and 13,000 species, divided into 13 tribes (some of which have been regarded on occasion as separate families). Alternate name: Asteraceae. There are 32 genera reported from Guam (usually represented by but a single species); however only 3 can be considered indigenous while another 15 genera are fairly frequently encountered as naturalized weeds. The remaining 14 genera are found only in cultivation, or are weedy but quite rare. Indigenous genera: Adenostemma; Glossogyne; Wedelia. Naturalized weeds; Ageratum; Bidens; Conyza; Crassocephalum; Eclipta; Elephantopus; Emilia; Mikania; Pluchea; Pseudelephantopus; Synedrella; Tridax; Vernonia; Youngia. Naturalized but rare weeds: Artemisia; Blumea; Erigeron; Eupatorium; Sonchus. Cultivated: Artemisia; Aster; Chrysanthemum; Coreopsis; Cosmos; Cynara; Gaillardia; Lactuca [also occasionally weedy]; Tagetes; Zinnia.