Flowers often well-developed and showy, corolla with fused petals, stamens attached to corolla tube, often with two fused carpels.

Leaves simple or less often compound or dissected.

11 orders, 49 families, 60,000 species

20,000 species are in the Asteraceae

Diagnostic characteristics: sympetalous flowers, epipetalous stamens isomerous and alternate with the corolla-lobes or less than the corolla lobes

Chemically, iridoids are frequent, with the exception of the Asteraceae

The Asteridae is the most advanced class of dicots. They utilize specialized pollinators and specialized means of presenting the pollen. "Rise of the Asteridae is closely correlated with evolution of insects capable of recognizing complex floral patterns" - A. Cronquist.