KEY TO FAMILIES. 9 



Flowers 2 or 3 to each scale or bract; staminate catkin long, pendulous, 

 the pistillate 1 small, spike-like, maturing into a woody cone containing 



margined achenes Alxus, p. 121. 



Only the staminate (rarely the pistillate) flowers in catkins. 



Fruit a nut enclosed in a leafy tubular involucre Corylus, p. 121. 



Fruit a nut set in a scaly cup or bur (acorn or chestnut) . Fagaceae, p. 121. 



B. Flowers not in catkins. 



1. Trees, shrubs, or woody cumbers. 



a. Leaves opposite; flowers dioecious or polygamo-dioecious. 



Ovary interior; fruit a berry; leaves simple, foliaceous or scale-like; parasitic 



Oil trees LiORANTHACEAE, p. 307. 



Ovary superior; leaves pinnate; trees or climbers; 



Stamens 4 or 5 ; fruit a double samara Acer, p. 250. 



Stamens commonly 2; fruit a simple samara Fraxixus, p. 319. 



Stamens numerous; sepals 4, petal-like; fruit a tailed achene; climbing 

 plants Clematis, p. 168. 



1). Leaves alternatt and simple. 

 Flowers monoecious, in head-like clusters scattered on a slender axis; calyx 



none Plataxaceae, p. 126. 



Flowers perfect or unisexual; sepals and stamens 4 or 5; fruit berry-like.... 



Rhamnus, p. 251. 

 Flowers perfect. 



Stamens 6 to numerous. 

 Erect trees or shrubs. 



Calyx of 6 petal-like sepals; stamens 9, the anthers opening by valves; 



fruit a drupe; evergreen Lauraceae, p. 174. 



Calyx 5-lobed; stamens numerous, 25 to 60, inserted on the calyx; fruit 



a tailed achene Cercocarpus, p. 205. 



Calyx 4-cleft, corolla-like; low shrub with tough leathery stems 



Thymeleaceae, p. 256. 

 Climbing plant; calyx tubular; stamens 6, anthers sessile; capsule 6- 



celled Aristolochia, p. 307. 



Stamens 5, monadelphous; calyx 5-cleft; showy; capsule 4 or 5-celled 



Fremoxtia, p. 262. 

 Stamens 1 or 2; calyx of 4 or 5 sepals; leaves scale-like; fruit a utricle. . . 



Spirostachys, p. 145. 

 2. Herbs. 

 a. Ovary superior, i. e., free from the calyx. 

 y Calyx present; corolla none. 

 Pistil 1, 1-celled; stigmas or styles often more than one. 

 Stipule* present. 



Leaves alternate ; fruit an achene. 



Stipules sheathing, scarions; calyx ." to 6-cleft or -parted, or of distinct 

 sepals, often petal-like; stamens 4 to 9; fruit a 3-sided or lenticular 



achene Polygoxaceak, p. Ills. 



Stipules not sheathing; calyx greenish; stamens 1 to 4. 



Flowers monoecious, very small, in catkin-like Inflorescences; plants 



with stinging herbage Crticaceak, p. L26. 



Flowers perfect, fascicled; diminutive annual. . Alchemilla, p. 210. 



