Asteraceae, also called Compositae, the aster, daisy, or composite family of the flowering-plant order Asterales. With more than 1,620 genera and 23,600 species of herbs, shrubs, and trees distributed throughout the world, Asteraceae is one of the largest plant families.
Members of the family have flower heads composed of many small flowers, called florets, that are surrounded by bracts (leaflike structures). Bell-shaped disk florets form the centre of each head. Strap-shaped ray florets extend out like petals from the centre and are sometimes reflexed (bent back). Some species have flowers with only disk or only ray florets. The sepals have been reduced to a ring of hairs, scales, or bristles that is called the pappus on the mature fruit. The one-seeded fruit (an achene) has a hard outer covering.
The family is characterized by having a capitulum or head, an inferior, unilocular ovary with one ovule, and with few exceptions fused anthers surrounding the style. The capitulum (capitula plural) is a specialized indeterminate inflorescence that can contain 1 to hundreds of individual flowers (florets). The flowering sequence in the capitulum is nearly always from the outside to the center, that is, centripetal. The florets sit on the disc or receptacle, an expanded shoot that can be flat, concave, convex, or rarely columnar. The disc and florets are surrounded by bracts or leaf-like structures called phyllaries and collectively forming an involucre. The phyllaries can be arranged in one row and be of equivalent length or can be unequal in length. Most sunflowers have involucres with several series of phyllaries. In these sunflowers the phyllaries can be subequal with all phyllaries of equivalent length or imbricate. Involucres composed of imbricate phyllaries are the most common condition in the family and exemplified by the artichoke (Cynara cardunculus) in which multiple series of phyllaries overlap each other. In some species the outermost phyllaries sometimes resemble leaves. The receptacle can be naked or sometimes have bract-like structures called paleae, scales or hairs surrounding each floret. The involucre can have different shapes ranging from tubular to hemispheric.
Some examples of plants from Magnoliaceae familia are:
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