Asteraceae

 

ASTERACEAE

Bercht. & J.Presl 1820

pronounced: ass-ter-AY-see-eye

the daisy family

also known as

COMPOSITAE

 

Asteraceae is derived from the Greek αστηρ (astér), a star. This is one of the largest of all the plant families, with something like 20,000 – 25,000 species worldwide. It is highly relevant to human life, as it includes economic, culinary and medicinal plants such as sunflower, lettuce, chicory, artichoke, chamomile, absinthe and tarragon, as well as numerous ornamentals and many plants that are considered to be weeds. The main characteristic of the daisy family is the inflorescence. What appears at first sight to be a single flower is actually a composite of many smaller flowers. There are hundreds of tiny flowers growing on a disk, each producing only one seed. Each disk floret has 5 tiny petals fused together, plus 5 stamens fused around a pistil with antennae-like stigmas. Each big “petal” of those that ring the outside of the flower head is also a flower, known as a ray floret, with its petals fused together and hanging to one side. Plants may produce disk florets or ray florets or both. What appear to be sepals outside the flower head are actually bracts, modified leaves.

 
Photograph © Donald Simpson 2008