URTICA 
99 
Genus i. Urtica 
Urtica [Tournefort Inst. 534, t. 308 (1719)] L. Sp. PI. 983 (1753) et Gen. PI. ed. 5, 423 (1754); Engler 
in Engler und Prantl Pflansenfam. Hi, pt. i, 104 (1894). 
Shrubs (rarely) ; or herbs, perennial or (rarely) annual ; with stinging hairs. Leaves opposite 
and decussate, stipulate, simple. Inflorescences of compound catkins, sometimes agglomerated into 
subspherical heads. Bracts absent. Flowers dioecious or diclinous. Perianth 4-partite, segments 
imbricate in bud (as in Ulmus ), persistent, of the staminate flowers concave, of the pistillate flowers 
flat. Stamens 4. Anthers reniform. Stigmas subsessile, penicillate. Fruit a compressed achene. 
About 30 species ; temperate zones. 
British species of Urtica 
1. U. dioica (see below). Perennial. Inflorescences catkinate, dioecious. 
2. U. urens (p. 100). Annual. Inflorescences catkinate, diclinous, each with staminate and 
pistillate flowers. 
3. tU. pilulifera (p. 100). Annual. Inflorescences diclinous; staminate ones lax-flowered; 
pistillate ones peduncled, flowers agglomerated in a globose head. 
I. URTICA DIOICA. Common Stinging Nettle. Plate 107 
Urtica urens Gerard Herb. 570 (1597); U. racemifera major perennis Ray Syn. ed. 3, 139 (1724). 
Urtica dioica L. Sp. PL 984 (1753); Syme Eng. Bot. viii, 127 (1868); Rouy Ft. France xii, 272 (1910); 
Ascherson und Graebner Syn. iv, 607 (191 1). 
leones : — Curtis FI. Lond. i, t. 196; Smith Eng. Bot. t. 1750 (1807); FI. Dan. t. 746 (1782); Reichenbach Icon. 
xii, t. 654, fig. 1324 (left-hand drawing). 
Camb. Brit. FI. ii. Plate 10J. (a) Shoot with staminate catkins, (b) Shoot (of f. angustifolia) with 
pistillate catkins, (c) Staminate flowers (enlarged). ( d ) Pistillate flower, pistil, and fruits (enlarged). Huntingdon 
(E. W. H.). 
Exsiccata : — Billot, 457 ; Herb. FI. Ingric. iv, 579. 
Perennial. Rhizome stout. Stem up to about 1 m. high, erect, more or legs branched. Petioles 
long (1—4 cm.). Laminae broadly or narrowly ovate, cordate or rounded at the base, strongly 
serrate, acute to acuminate, up to about 12 cm. long and 9 broad. Catkins dioecious. Staminate 
catkins spreading. Pistillate catkins descending. July to September. 
(/ 3 ) forma angustifolia comb. nov. ; U. dioica var. angustifolia Wimmer et Grabowski FI. Silic. iii, 336 
(1829); Ledebour FI. Alt. iv, 241 (1833). 
leones : — Reichenbach Icon. t. 654, fig. 1324 (middle drawing), as U. dioica. 
Camb. Brit. FI. ii. Plate ioj. (b) Shoot with pistillate catkins. 
Laminae much narrower. 
A form of sunny situations and dry soils. 
(7) forma microphylla comb, nov.; U. dioica var. microphylla Hausmann FI. Tir. 771 (1854). 
Laminae as narrow as in f. angustifolia but much shorter. 
A form of sunny situations and very dry soils. 
Other forms are said to vary with regard to the degree of venomousness. 
It is curious that this species, and others with nitrophilous tendencies, will grow well either in somewhat exposed 
situations when the nitrogen-content of the soil is high, or in shady places where the nitrogen-content of the soil is apparently 
low. 
Indigenous throughout the British Isles, in waste places and on roadsides, in damp woods, 
hedgerows, and plantations, and in sheltered places on mountain-sides where sheep and cattle lie ; 
ascending to about 840 m. in Perthshire ; nitrophilous. 
Europe, ascending to 2380m. in the Alps; Asia; northern Africa; Polynesia; America (not 
indigenous). 
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