496 



URTICACE^E. 



1019. Order 166. Urticaceas, the Nettle Family. (Apet. Diclin.} 

 Flowers unisexual (fig. 716), hermaphrodite or polygamous, scattered, 

 or collected into catkins or heads. Perianth usually divided (fig. 

 716). Stamens definite, inserted into the perianth ; filaments some- 

 times curved in aestivation (fig. 715). Ovary free (figs. 717, 718), 

 rarely coherent, 1-2-celled ; ovule solitary, erect (fig. 718), or sus- 

 pended; stigmas 1 or 2, simple or bifid (fig. 718). Fruit an inde- 

 hiscent nut, surrounded by the persistent pericarp, or a samara, or a 



718 



syconus, or a sorosis (figs. 245, 246, 475). Seed solitary, erect, 

 suspended, or pendulous, albuminous or exalbuminous ; embryo 

 straight, or curved, or spiral; radicle superior (figs. 719, 720). 



Fig. 714-720. Organs of fructification of Urtica urens, to illustrate the natural order Urti- 

 cacese, section Urticeae. 



Fig. 714. Bud of the male flower, viewed from above. 



Fig. 715. Stamen taken from the hud of the male flower, with the elastic incurved filament, 

 and the anther bent down before dehiscence. 



Fig. 716. Male flower expanded, c, Perianth with four divisions, e e e e. Four hypogynous 

 stamens, thrown back by the elasticity of the filaments, with the anthers burst, p r, Abortive 

 rudiment of the central pistil. 



Fig. 717 Female flower, c, Perianth with four unequal segments, the two exterior ones 

 being very small, o, Unilocular ovary, s, Sessile stigma. 



Fig. 718. Pistil cut vertically, to show the direction of the erect ovule, o. p, Parietes of the 

 ovary, s, Stigma. 



Fig. 719 Seed cut vertically, parallel to the cotyledons, t, Integument (spermoderm). 

 A, HUum. p, Perisperm. e, Embryo straight, with the radicle superior. 



Fig. 720. Seed cut perpendicularly to the cotyledons, t. Integument, h, Hilum. p, Peri- 

 sperm, e. Embryo. 



