166 



DE CANDOLLE'S SYSTEM. 



Populus. 1. Nigra. 2. Tremula. 3. A male flower. 4. A female flower. 5. 

 A ripe capsule. 6. A seed. 



147. Platanacea. Trees or shrubs. Leaves alternate, 

 with scarious sheathing stipules. Flowers amentaceous, in 

 round unisexual catkins. Stamens single. Ovaries termi- 

 nated by a thick style, having the stigmatic surface on one 

 side ; ovules solitary, or two, suspended. Nuts clavate. 

 Seeds solitary ; embryo in the axis of fleshy albumen. 



USES. The large species yield a beautiful but brittle and 

 perishable timber. 



TYPICAL GENUS. Platanus. 



148. Urticacea. Trees, shrubs or herbs, sometimes lac- 

 tescent. Leaves alternate, usually covered with asperities 

 or stinging hairs; with stipules. Flowers small, monoecious 

 or dioecious. Calyx membranous. Stamens definite, often 

 turned back with elasticity. Ovary superior, simple; ovule 



