pyrethrum (redirected from genus Pyrethrum)

pyrethrum (pīrē`thrəm): see chrysanthemum.

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pyrethrum

Any of certain plant species of the genus Chrysanthemum (see chrysanthemum) native to South Asia, whose aromatic flower heads, when powdered, constitute the active ingredient in the insecticide pyrethrin (or pyrethrum). The concentrations of pyrethrum powder used in insecticides are nontoxic to plants and higher animals; these insecticides therefore find wide use in household and livestock sprays as well as in dusts for edible plants. The typical species, the perennial C. coccineum, also is the florists' pyrethrum, or painted lady. Large petals of a deep rose colour surrounding the yellow centre, or disk, are borne on long simple stems above the crown of finely cut leaves.

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pyrethrum

1. any of several cultivated Eurasian chrysanthemums, such as Chrysanthemum coccineum and C. roseum, with white, pink, red, or purple flowers pyretic

Pathol of, relating to, or characterized by fever

3. any insecticide prepared from the dried flowers of any of these plants, esp C. roseum

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pyrethrum [pī′rē·thrəm]

(materials)

A toxicant obtained in the form of dried powdered flowers of the plant of the same name; mixed with petroleum distillates, it is used as an insecticide.