MERCURIALIS PERENNIS.— PERENNIAL, OR DOG’S MERCURY. 
Class XXII. DICECIA. Order VIII. ENNEANDRIA. 
Natural Order, EUPHORBIACE^. THE EUPHORBIUM TRIBE. 
Fig. (a) represents the calyx ; (6) a single fertile flower ; (c) the capsule and seeds ; (d) the stamens, with their anthers, and the calyx. 
Two species of this genus are indigenous to Britain, viz. the perennial or Dog’s Mercury, (Mercurialis 
perennis ,) and the annual or French Mercury, (Mercurialis annua.) The former has obtained a place in our 
work on account of its poisonous qualities, and the latter was at one time in considerable repute as an 
article of the materia medica. Dog’s Mercury is a common plant, growing everywhere in shady groves and 
hedges ; flowering in April and May. 
The root is creeping, white, and very fibrous. The stem is erect, perfectly simple, round, leafy, naked 
below, thickest at the joints, slightly winged alternately, and rises to the height of a foot or more. The 
leaves stand in opposite pairs, on short footstalks; they are ovate, acute, serrated, two or three inches long, 
with two small pointed stipules, at the base of the footstalks. The flowers proceed in slender, erect spikes, 
from the axillae of the leaves, near the top of the stem ; in the barren, or male plant, longer than the leaves ; 
in the female, concealed among them. The flowers in the fertile plant are few ; in the barren ones nume- 
rous, sessile, growing in a short, interrupted spike, and half surrounding the stem. The barren flowers 
have from nine to twelve capillary, erect stamens, bearing globular, two-lobed anthers : there is no corolla, 
and the calyx in both, is divided into three deep, ovate, concave, spreading segments. The germen is supe- 
rior, roundish, compressed with a furrow at each side, supporting two spreading, inflexed, tapering, rough 
styles, having acute stigmas. Two awl-shaped bodies, found occasionally at the opposite side of the germen, 
and rising above the styles, are supposed to be the nectaries. The seed-vessel is two-lobed, globular ; 
capsule two-celled, and containing a single roundish seed in each cell, of a brownish purple colour. 
Qualities. — The whole herb has a very nauseous taste, and a heavy, disagreeable odour. When 
dried, the leaves often assume a bluish tint, indicating its affinity, as a distinguished writer in Rees’ Cyclo- 
pedia has well remarked, to Croton tinctorium. Notwithstanding its strong unpleasant flavour, Dog’s 
Mercury has been eaten boiled as a pot-herb, when mixed with mucilaginous and oily substances ; yet 
instances are not wanting of the fatal consequences of its use occasionally in this country. The following 
case, where it was mistaken for common English mercury, (Chenopodium Bonus Henricus,) and had nearly 
proved fatal to a whole family, is recorded by Sir Hans Sloane, in the 3rd edition of Ray’s 
Synopsis: — 
“ W. Matthews, his wife, and three children, have been lately very ill, and like to die ; the occasion and 
manner of their sickness was very odd, and therefore I shall give you a particular account of both. About 
three weeks ago, the woman went into the fields and gathered some herbs, and, having first boiled them, 
fried them with bacon for her own and her family’s supper. After they had been about two hours in bed, 
one of the children (which is dumb, and about seven years old) fell very sick, and so did the other two 
presently after, which obliged the man and his wife to rise and take the children to the fire, where they 
vomited &c. and within half an hour fell fast asleep. They took the children to bed as they were asleep, and 
they themselves went to bed too, and fell faster asleep than they had ever done before. The man awoke 
next morning about three hours after his usual time, went to his labour at Mr. Newport’s, and so by the 
strength of his constitution carried it off ; but he says he thought his chin had been all day in a fire, and 
was forced to keep his hat full of water by him all day long, and frequently dipt his chin in it as he was at 
work. The woman awoke awhile after her husband, and, being forced to it, got up to look after her little 
family concerns ; but she was very sick, and has continued so till within these few days, since she is very well 
