Composite family
= Family Asteraceae
Description
The largest family of flowering plants, representing almost every life form including evergreen shrubs, annual-, biennial- and perennial herbs (Compositae 1). The family has a cosmopolitan distribution with many genera in the semi-aride regions of the tropics and subtropics.
Leaves are very variable, simple or compound, often lobed or dentate. The inflorescence is very characteristic. The individual flowers are small, but clustered into heads (capitulae) they resemble large flowers. These small flowers or florets, unisexual or bisexual, are seated on receptacles of varied form, and the heads are surrounded by a whorl of bracts (involucre), or bracts resembling a calyx. The florets often have no calyx, and sometimes a tuft of hairs or bristles develops. The corolla is tubular or straplike, 5-lobed. There are 5 stamens joined in a tube. The ovary is inferior and 1-celled. The fruit is a single-seeded dry and indehiscent fruit (achene).
Some forms have all florets similar, either all tubular or all strap-like (Compositae 2); in others the outer florets are strap-like, female or neuter, while the inner florets are tubular and usually hermaphrodite.
There are over 1000 genera.
Use
The family includes many cultivated plants like vegetables, e.g. lettuce, endive, artichoke, chicory and scorzonera; oil-producing plants, e.g. sunflower, safflower and niger seed; and plants used as flavouring, e.g. chamomile, wormwood, tarragon and southernwood. Pyrethrum is grown for insecticides.
Described species
Chrysanthemum cinerariaefolium, pyrethrum
Matricaria chamomilla, chamomile, see Chrysanthemum cinerariaefolium
Artemisia absinthium, wormwood, see Chrysanthemum cinerariaefolium
Artemisia dracunculus, tarragon, see Chrysanthemum cinerariaefolium
Artemisia abrotanum, southernwood, see Chrysanthemum cinerariaefolium
Chrysanthemum coronarium, garland chrysanthemum, see Lactuca sativa
Cynara scolomys, artichoke
Cynara cardunculus, cardoon, see Cynara scolomys
Scorzonera hispanica, scorzonera
Tragopagon porrifolius, Spanish salsify, see Scorzonera hispanica
Arctium lappa, burdock, see Scorzonera hispanica
Cichorium endivia, endive
Cichorium intybus, chicory
Lactuca sativa, lettuce
Helianthus annuus, sunflower
Helianthus tuberosus, Jerusalem artichoke, see Helianthus annuus
Carthamus tinctorius, safflower
Guizotia abyssinica, niger seed