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Family: Asteraceae Bercht. & J.Presl

Kingdom: Plantae Rank: Family Parent: Asterales Status: Valid

Common Names:

  • SUNFLOWER FAMILY - English, United States of America
  • DAISY FAMILY - English, United States of America

Morphological Description

Family Recognition in the Field: Usually herbs or rarely shurbs with a characteristic inflorescence: flowers in a compact head subtended by bracts (= phyllaries)—the inflorescence resembling a single flower (the heads are often grouped together to form compound inflorescences); corollas sympetalous, 5-merous; stamens united by their anthers; fruit a 1-seeded achene often topped by a pappus of hairs, scales, or teeth.

Diagnosis: Annual or perennial herbs or more rarely shrubs; leaves basal, alternate, opposite, or whorled, simple or compound, entire, toothed, or lobed, not stipulate (but small basal lobes sometimes resemble stipules); inflorescence a single involucrate head, or several or many involucrate heads in corymbs, racemes, or panicles, each head simulating a single flower; involucre of one or more rows of separate or united bracts (termed phyllaries to avoid confusion with bracts on peduncles) imitating sepals; flowers (= florets) without typical calyx, but commonly with modified calyx of hairs, scales, or teeth (= pappus) on summit of the inferior ovary; corollas of two basic types: disk, mainly tubular (varying from thread-like to tubular-funnelform or campanulate with cylindrical basal tube), with 4 or 5 equal or unequal teeth or lobes; and ray, with small basal tube and broad, strap-shaped main portion (= ligule); stamens none or 5, attached inside the corolla tube; anthers separate or united into a ring; pistil 1; style 1, commonly with 2 branches; ovary inferior; fruit an achene.

Other

Ecology: Some species are toxic in nature.

Notes: The Asteraceae is one of the two largest families of flowering plants (Orchidaceae is the other), containing ca. 21,000-25,000 species (22,750 species in 1,528 genera-Mabberley 1997). It is a cosmopolitan family of mainly herbs to shrubs and is of significant economic importance as a source of food plants (e.g., Lactuca-LETTUCE, Cynara scolymus L.-ARTICHOKE), oil (e.g., Helianthus-SUNFLOWER and Carthamus-SAFFLOWER), and numerous ornamentals (e.g., Aster, Bidens, Cosmos, Dahlia , Helianthus, Tagetes-MARIGOLD). Many are weeds including Taraxacum species (DANDELIONS) and Cirsium species (THISTLES); in some parts of the world poisonous species of Senecio are a major cause of livestock poisoning; wind-pollinated genera such as Ambrosia (RAGWEED), Iva (SUMPWEED), and Artemisia (SAGEBRUSH), which produce large quantities of allergenic pollen, are important causes of hay fever (Lewis et al. 1983). Cronquist (1981) suggested that the evolutionary success of the family may be in part due to a diversified chemical defense system, including polyacetylenes and sesquiterpene lactones. The 351 species of Asteraceae found in OK make it the largest family in that state (Taylor & Taylor 1994) and the 620 species (almost 13% of the TX flora) in TX likewise make it the largest TX family (Hatch et al. 1990). The Asteraceae is also the largest family in the nc TX flora; the 263 species represent nearly 12% of the 2,223 species known in nc TX. (subclass Asteridae)