CLASS XXI. ORDER Iv, | URTICA. 1193 
concave pieces, more or less hairy. Seed ovate, compressed, pale 
brown, polished. 
Habitat.—W aste and cultivated ground ; very common. 
Annual ; flowering from June to October. 
A very variable plant in size, according to the situation and kind 
of soil in which it grows. 
3. U. diot'ca, Linn. (Fig. 1452.) Great Nettle. Leaves opposite, 
oblong, heart-shaped, coarsely serrated; panicles axillary, much 
branched, longer than the petioles, mostly dicecious. 
English Botany, t. 1750.—-English Flora, vol. iv. p. 185.—Hooker, 
British Flora, ed. 4. vol. i. p. 135.—Lindley, Synopsis, p. 219. 
Root long, creeping, and with deep fibrous branches. Stem erect, 
about three feet high, obtusely four angled and furrowed, mostly a 
dull purple, simple or branched, leafy, and very hairy. Leaves large, 
rough, opposite, spreading, oblong, heart-shaped, with a more or less 
tapering point, coarsely serrated, with large often compound teeth, a 
deep dull green, paler beneath the mid-rib, and spreading lateral 
branches prominent. Inflorescence axillary much branched spread- 
ing paniculated racemes, longer than the leaf stalks, the perianth of 
ovate concave hairy pieces. Fruit ovate, acute, compressed. 
Habitat —Waste places, under hedges and walls; frequent. 
Perennial; flowering in July and August. 
The Nettles are well known as troublesome weeds in gardens, 
hedges, &c., and almost every rambler in the fields or incautious 
gardener is acquainted with the effect of their poisonous weapons. 
The rigid hairs with which they are furnished, when examined with a 
magnifying power, will be found all of a tubular form, tapering to 
a fine open point, the base being dilated into an oblong receptacle, 
having at the bottom a gland embedded in the cellular substance 
of the leaf. This gland secretes an acrid juice, and is retained in the 
receptacle; thus furnished, when any obtrusive hand is applied to the 
point, it readily enters the skin, and the pressure forces the fluid 
along the tube into the wound it has made. This remarkable con- 
trivance is very similar to the structure of the poisonous fangs of the 
rattle-snake, viper, &c., and differs from the sting of the wasp in being 
open at the apex, while that of the wasp has the opening below the 
point, so that this little insect is ever furnished with a ready weapon, 
which is less liable to become deranged from repeated use by the 
point being more acute; and the opening being on one side below, it 
is less liable to become obstructed, a contrivance admirably adapted 
in each case or the uses for which the arms are required. 
The painful swellings and inflammations caused by the sting of 
our common Nettles in some persons is very considerable ; but it is 
nothing in comparison with that produced by some of the Indian 
species. M. Leschenault Mem. Mus. 6. 362. gives the following 
