(Asteraceae) One of the largest dicotyledonous families containing about 25 000 species in about 1100 genera and commonly referred to as the daisy or sunflower family. Its members are recognized by their characteristic headlike inflorescence, the * capitulum, which superficially appears to be a single flower. The fruit (see cypsela) often possesses a ring of hairs, the * pappus, to aid dispersal. All composites have resin canals except most of those in the tribe Lactuceae, which have latex ducts. Commercially important composites include the sunflower (Helianthus annuus), grown for the oil in its seeds, and lettuce (Lactuca sativa), and numerous,ornamental species, e.g. Dahlia, Chrysanthemum, and Aster. |
