UBTIGAOEM. 499 



number of long papillose hairs, caducous or persistent, which play 

 the part of a stigma. Near the base of the single cell, is inserted on 

 the posterior wall a single ovule, almost erect and orthotropous, 1 

 with a very short funicle, and the micropyle superior. 2 The fruit is 

 an oblong or oval compressed achene, often warty, surrounded by 

 the persistent perianth. The orthotropal seed contains a fleshy 

 albumen, enclosing in its axis the embryo, whose radicle is superior, 

 cylindro-conoidal, while the cotyledons are rounded or elliptical, 

 subcordate at the base. The Nettles are herbaceous annuals or 

 perennials, rarely frutescent, cosmopolitan, especially frequent in 

 the Temperate regions of both Worlds, with most of their organs 

 usually covered with stinging hairs of peculiar structure, 3 Upwards 

 of seventy species have been described, but their number is now 

 reduced by about one-half. 4 Their branches are often tetragonal, 

 covered with opposite leaves, often dentate, rarely incised lobate, 

 palmiveined, rarely tricostate, more frequently 5-7-ribbed, petiolate, 

 with two lateral stipules, often connate with those of the opposite 

 leaf. The blade is often sprinkled with cystoliths, punctate or more 

 rarely elongated-linear, prominent in the dry leaf. 5 The flowers are 

 in glomerules, grouped along a common axillary axis into capitula 

 (fig. 533), or simple or ramified racemes or spikes, often unilateral, 

 and are dioecious or monoecious ; in the latter case the inflorescences 

 may be unisexual or androgynous. 



Next to Urtica come the two genera Nanocnide and Hesperocnide. 

 They have the same general organization and straight fruit ; but 

 the one has alternate leaves, and the two lateral sepals of the female 



1 Sometimes a little arcuate, like that of the the tip of the hair breaks off; the skin is iriocu- 

 Planes, especially before maturity, and more lated with it by the penetration of the hair. The 

 convex hi front than behind. base of the sting is surrounded by a sheath of 



2 It has two coats. prominent cells belonging to the subepidermic 



3 Douval-Jouye has shown (in Bull. Soc. Bot. parenchyma, and these are supposed to secrete 

 de Fr., xiv. 36, t. 1) that the Nettles have three the irritant liquid which then passes into the hair 

 sorts of hairs: (1) Short, invisible to the naked like a reservoir. This hair is merely an elongated 

 eye, not urticating, with a unicellular cylindrical epidermic cell. Its wall is hollowed by interstitial 

 stem, and a swollen head formed of 2—4 cells. vacuoles, forming shining interrupted spiral lines. 

 (2) Elongated conical, "unicellular, with finely (See DC, Fl. Fr., iii. 322. — A. Juss., Eleni., 

 dotted walls. (3) The sting or stimulus, urti- 151. — Barhaedt, De Bills FL, Bonn. (1849). — 

 eating simple, long-conical, unicellular, formed of Wedd., Monogr., 9. — Duciitre, Mem., 99.) 



a dilated basilar bulb, a conical stylet continuous 4 Wedd., Brodr., 39-59, 235 c3 . 



with it. and a little inclined tip swollen into a 5 See Wedd., Sur les Cystolithes... des Ur- 



ball. The whole is hollow, filled with an acid, ticees (in Ann. Sc. Nat., ser. 4, ii. 207). 

 irritant liquid, which gives a burning pain when 



K K 2 



