(Greek, golden flower). Including Pyrethrum. Compósitae. A large genus of herbaceous and sub-shrubby plants, mostly hardy, and typically with white or yellow single flowers., but the more important kinds greatly modified in form and color.
Bentham & Hooker make 22 subgenera (of which about 6 include the garden forms), based chiefly on the manner in which the seeds are ribbed, cornered, or winged, and the form of the pappus. The garden Pyrethrums cannot be kept distinct from Chrysanthemums by garden characters. The garden conception of Pyrethrum is a group of hardy herbaceous plants, with mostly single flowers, as opposed to the florists' or autumn
Chrysanthemums, which reach perfection only under glass, and the familiar annual kinds, which are commonly called Summer Chrysanthemums. When the gardener speaks of “Pyrethrums”, he usually means P.roseum.
Many of the species described below have been called Pyrethrums at various times, but they all have the same specific name under the genus Chrysanthemum, except the most important of all garden Pyrethrums. P. roseum, which is C.coccineum. The Feverfew and Golden Feather are still sold as Pyrethrums, and the only other species of importance is is P.uliginosum.