Daisy

Daisy — The family Asteraceae or Compositae, known as the aster, daisy or sunflower family, is the second largest family of flowering plants, after Orchidaceae, in terms of number of species.

The name ‘Asteraceae’ is derived from the type genus Aster, while ‘Compositae’, an older but still valid name, means composite and refers to the peculiar inflorescence.

According to the Royal Botanical Gardens of Kew the family comprises more than 1,600 genera and 23,000 species. The largest genera are Senecio (1,500 species), Vernonia (1,000 species), Cousinia (600 species), Centaurea (600 species). The circumscription of the genera is often problematic and some of these have been frequently divided into minor subgroups.

Asteraceae are most usually herbs, but some trees and climbers do exist. They are generally easy to distinguish, mainly because of their peculiar inflorescence and share many apomorphies.

The most evident characteristic of Asteraceae is perhaps their inflorescence: a specialised capitulum, technically called a calathid or calathidium, but generally referred to as flower head or, alternatively, simply capitulum. The capitulum is a contracted raceme composed of numerous individual sessile flowers, called the florets, that share the same receptacle.