Unicoi LXXI. URTIOACEJE. 399 



Erect herbs. Leaves opposite 1. Urtioa. 



Erect or procumbent herb. Leaves alternate 2. Parietaria. 



Tall twiner. Leaves opposite 3. Humulus. 



Among exotic genera in cultivation may be mentioned the Hemp 

 {Cannabis), which, although an erect herb, is in many respects allied to 

 the Hop; the Fig (Ficus), in which the flowers are collected in great 

 numbers withinside a succulent receptacle, popularly called the fruit ; 

 and the Mulberry (Moms), in which the flowers are collected in heads on 

 the outside of a receptacle, and become succulent as the fruit ripens. 



I. URTICA. NETTLE. 



Erect herbs, with stinging hairs and opposite leaves. Flowers in 

 axillary clusters or spikes ; the males with a perianth of 4 segments 

 and 4 stamens ; the females with a perianth of 2 segments, or, if 4, the 

 2 inner ones larger. Fruit a flattened seed-like nut, enclosed in the 

 perianth. Stigma single, sessile, and tufted. 



A considerable genus, generally distributed over the globe. 



Annual and monoecious. Flowers in nearly sessile short clusters . 1. IT. urens. 

 Annual and monoecious. Male flowers in loose spikes. Females 



in stalked, globular heads 2. IT. pUulifera. 



Perennial, usually dioecious. Flowers in branched spikes . . 3. IT. dioica. 



1. U. urens, Linn. (fig. 903). Small N. — An erect, branching annual, 

 seldom above a foot high and often only a few inches, glabrous with the 

 exception of the stiff, stinging hairs. Leaves ovate or elliptical, deeply 

 and regularly toothed, more tender than in the two other species. 

 Flowers male and female intermixed, in small, loose, almost sessile 

 axillary clusters. 



In cultivated and waste places, especially in rich soils, throughout 

 Europe and temperate Asia, and carried out as weed of cultivation to 

 other parts of the world. Common in Britain. Fl. the whole season. 



2. TJ. pilulifera, Linn. (fig. 904). Roman N. — An annual like the 

 last, but coarser and taller, attaining 2 feet, and very stinging. Leaves 

 ovate or heart-shaped, deeply and regularly toothed. Male flowers in 

 little, distinct clusters, along peduncles often as long as the leaves ; the 

 females in globular heads, on the summit of a peduncle from J to 1 inch 

 long. When in fruit these heads are 4 or 5 lines in diameter, and 

 thickly beset with stinging bristles. 



On roadsides, and in waste places, in southern Europe. Farther 

 north only as an introduced weed in the neighbourhood of habitations, 

 and as such occurs occasionally in the east of England. Fl. summer and 

 autumn. U. Dodartii, Linn., is a variety with nearly entire leaves. 



3. TJ. dioica, Linn. (fig. 905). Common N. — Kootstock perennial and 

 creeping. Stems erect, 2 or 3 feet high, the whole plant of a dark 

 green, and more or less downy, besides the copious stinging bristles. 

 Lower leaves cordate- ovate, the upper ones more or less lanceolate, 

 narrowed at the point, coarsely toothed. Flowers usually dioecious, 

 both the males and females clustered in axillary, branched, spreading 

 spikes, usually about the length of the leaves. 



Along hedges, on roadsides, and in waste places throughout Europe 

 and Eussian Asia, from the Mediterranean to the Arctic regions, and 

 carried out as a weed to other parts of the globe. Common in Britain. 

 Fl. summer and, autumn. 



