Pyrethrum Pharm. Lond. & Edinb Pyrethrum flore bellidis C. B. Chamaemelum spe-cioso flore, radice longa fervida Shaw afr. Den-taria, herba salivaris, & pes alexandrinus qui-bufdam. Anthemis Pyrethrum Linn, Pellitory of Spain: a trailing perennial plant; with finely divided leaves somewhat like those of camomile or fennel •, and naked thick stalks, bearing each a large flower, which consists of a yellow disk surrounded with petala of a pure white colour on the upper side, and a fine purple underneath: the root, which finks deep in the ground like a carrot, is of a brownish colour on the outside and whitish within. It is a native of the warmer climates, but bears the cold of our own, and often produces flowers in succession from January to May: the roots also, as Parkinson observes, grow larger with us, than those which the shops are supplied with from abroad.

(a) Mat, Med. 491.

Extract. fo-lior. pulfa-tillae nigri-cantis Ph, Ed.

Pellitory root has a very hot pungent taste, without any sensible smell. Its pungency re-sides in a resinous matter, of the more fixt kind; being extracted completely by rectified spirit, and only in small part by water; and not being carried off, in evaporation or distillation, by either menstruum. The spirituous extract is extremely fiery, but in small quantity, scarcely amounting to one twentieth of the weight of the root. The watery infusion is nauseous, but scarcely discovers any acrimony till concentrated by infpiffation; when reduced to the consistence of an extract, it proves considerably pungent: the quantity of this extract is commonly five or six times as large as that of the spirituous. The root remaining, after the action of water, yields still with rectified spirit a very fiery extract; whereas that, which has been digested in spirit, yields with water only an insipid mucilaginous substance.

The principal use of pyrethrum, in the pre-sent practice, is as a mafticatory, for stimulating the salival glands, etc. and evacuating viscid humours from the head and parts adjacent: by this means it frequently relieves tooth-achs, some kinds of head-achs, lethargic complaints, and paralyses of the tongue. it has sometimes likewise been given internally, from a few grains to a scruple, as a hot stimulant and attenuant, in paralytic and rheumatic disorders.