compositae

Century Dictionary and Cyclopedia

1. The largest natural order of plants, including over 750 genera and 10,000 species, distributed all over the globe wherever vegetation is found, and divided equally between the old world and the new. They form about a tenth of all phenogamous plants, an eighth of those of North America, and in some regions even a larger proportion. They are herbs, or much more rarely shrubs, scarcely ever arborescent, and are of comparatively slight economic importance. A few species are cultivated for food, as the artichoke (Cynara), the salsify (Tragopogon), and the lettuce (Lactuca); others have useful medicinal properties; and a very large number are cultivated for ornament. The flowers are gamopetalous and mostly pentamerous, sessile in a close head (the compound flower of early botanists, whence the name of the order), and surrounded by an involucre of separate or connate bracts. The ovary is inferior and one-celled, and becomes an achene in fruit, the calyx-limb being reduced to a circle of hairs, awns, scales, or teeth, called the pappus. The stamens are inserted on the corolla, and their anthers are united into a tube, on which account the name Synanthereœ has been sometimes given to the order. The genera of the order are divided into three series, depending upon the character of the corolla, viz.: the Labiatœflorœ (or Mutisiaceœ, of 59 genera, largely South American), having a bilabiate corolla, at least in the perfect flowers; the Liguliflorœ (or Cichoriaceœ, of 56 genera, mostly of the old world), in which the corollas are all ligulate (strap-shaped); and the Tubuliflorœ, having regular tubular corollas in all the perfect flowers. The last series is again divided into 11 tribes. The 10 largest genera of the order, including three tenths of the species, are Senecio (840 species, largely of South America and southern Africa), Eupatorium (430 species, all American), Vernonia (375 species, mostly tropical), Centaurea (316 species, of the Mediterraneo-Persian region), Baccharis (250 species, mostly South American), Helichrysum (235 species, of southern Africa and Australia), Aster (174 species, largely North American), Cnicus (165 species, of the Mediterraneo-Persian region and North America), Artemisia (152 species, of Europe, Asia, and North America), and Hieracium (150 species, of Europe, Asia, and North America). By far the largest North American genus is Aster (124 species), followed by Solidago (78), Erigeron (71), Senecio (57), Aplopappus (45), Artemisia (42), Helianthus (42), Eupatorium (39), Cnicus (37), Bigelovia (31), and Brickellia (31); these genera include two fifths of the species of North America. Also called Asteraceœ.
2. In zoology, a family of compound ascidians, corresponding to the family Botryllidœ; the Synascidiœ (which see).

GNU Webster's 1913

1. n. (Bot.) A large family of dicotyledonous plants, having their flowers arranged in dense heads of many small florets and their anthers united in a tube. The daisy, dandelion, and asters, are examples.

WordNet 3.0

1. n. plants with heads composed of many florets: aster; daisy; dandelion; goldenrod; marigold; lettuces; ragweed; sunflower; thistle; zinnia.