Asteraceae

Asteraceae or still validly called Compositae is the second most diverse family next to Orchidaceae. There are more than 1,600 genera and 23,000 species. The diversity within the genus is astonishing from tiny herbs to almost tree-like plants, from delicate and water-loving to desiccant tolerant succulents. Those living in harsh conditions have evolved silvery hairs which to reflect sunlight and conserve water. An amazing example of this is the Hawaiian silverswords Argyroxiphium sandwicense. Often times, the vegetative forms are so strange and different, one would never recognize them as belonging to the Asteraceae. However, the flower morphology are more or less conserved with two types of flowers, the ray and the disk flowers. Ray flowers are large conspicuous 'petals' which we see in daisies and sunflowers. Disk flowers are less conspicuous. Plants can have only rays (dandelions) only disks (Senecio spp.) or a combination of both (sunflowers). Flowers are often brightly colored to attract insect pollinators. Seeds are sometimes adorned with a pappus, which serves as an 'umbrella' to catch the wind. Other seeds employ sharp and sticky spurs or hairs which cling to animal fur. The Asteraceae is an economically important genus, mostly grown for their flowers (daisies, artichoke, chamomile, etc...). The leaves of some species are also aromatic and are used for both medicine and beverage preparation. Artemesia is an example of such use from folk medicine to preparation of absinthe. The genera from this family on the wiki are Dahlia, Helianthus, Liatris, and Smallanthus. These have species which are tuberous.


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Page last modified on February 14, 2015, at 06:21 AM