Daisy Family – Asteraceae or Compositae

The Family is named after the Latin and Greek word Aster which means a star. A huge family of over 1900 genera and 32,000 species with a worldwide distribution. The older name of Compositae refers to the  fact that what appears to be a single flower is in fact a composite of many smaller flowers called florets grouped together in a head or capitulum. There are 3 sub-families 1. Asteroideae – Sunflowers, Sneezeweed, Rudbeckia, Coneflower, Blanketflower, Achillea, Michaelmas Daisy, Everlasting, Elecampane, Daisy, Cosmos and Dahlia. 2. Carduoideae – Knapweeds, Cornflower, Thistles, Globe Artichoke, and Globe Thistle. 3. Chicoroideae – Dandelion, Chicory.

sunflower helianthus

Common Sunflower Helianthus annuus

spear thistle

Spear Thistle Cirsium vulgare

dandelion

Dandelion Taraxacum officinale

The inflorescence is a capitulum consisting of a head of hundreds of closely packed stalkless florets arising at the same flat level. The head is surrounded by a ring of green, sometimes spiny or hooked bracts. In some species, as shown here, there are 2 distinct types of floret, disc florets in which the corolla tube terminates in 5 short teeth and ray florets in which the tube extends into a strap or ligule. Florets may be bisexual, single sex or sterile. Often bisexual disc florets are at the centre and sterile ray florets are round the edge. In some species (dandelions) there are no disc florets so all florets are bisexual and strap-like. The outer ray flowers attract pollinators visually but the disc florets have nectaries at the base of the stamens and produce pollen during the initial male phase of pollination. After releasing pollen, the stigma lobes become receptive and pollinators, seeking nectar, bring pollen from another flower to ensure cross-pollination.