KEY TO THE FAMILIES 19 



Leaves alternate. 



Pistillate and staminate flowers both in catkins (or 

 cones). 

 Flowers 1 to each scale or bract. 



Seeds hairy, many in a capsule Salicaceae, 65 



Seed not hairy, solitary, in waxy-coated clus- 

 ters Myricaceae, 69 



Flowers 2 or 3 to each scale or bract ; seeds in a 



woody cone Betulaceae, 70 



Pistillate flowers not in catkins. 



Fruit a nut in a leafy tube Corylus, 70 



Fruit a nut in a scaly cup or bur (acorn or chest- 

 nut) Fagaceae, 71 



Flowers not in catkins. 

 Leaves opposite. 

 Ovary adherent to calyx; leaves simple; parasitic 



on trees Loranthaceae, 73 



Ovary free from calyx and corolla; leaves com- 

 pound. 



Climber ; fruit of many tailed akenes Clematis, 94 



Tree ; fruit long-winged Vraxinus, 185 



Leaves alternate, simple; erect trees and shrubs. 



Stamens 4 or 5 ; fruit berry-like Rhamnus, 154 



Stamens 9 ; fruit olive-like Lauraceae, 101 



Stamens numerous; fruit tailed, dry, 1-seeded 



Cercocarpus, 133 

 B. Herbs. 

 Calyx free from the ovary. (Ovary superior.) 



a. Pistils more than 1, distinct, becoming 1-seeded 



fruits ; stamens many Ranunculaceae, 94 



b. Pistil 1, 3-celled; calyx and corolla both wanting; 



flower-clusters surrounded by a petal-like in- 

 volucre ; juice milky Euphorbiaceae, 150 



c. Pistil 1, 4-celled; aquatic with hair-like leaves. 



Callitrichaceae, 151 



d. Pistil 1, 1-celled ; calyx present. 



Stipules sheathing the stem at the nodes .. Polygonaceae, 76 



Stipules present but not sheathing Urticaceae, 73 



Stipules none. 



Fruit a several-seeded capsule; styles 3 to 5 



Caryophyllaceae, 88 

 Fruit 1-celled, 1-seeded. 

 Flowers in clusters surrounded by an invo- 

 lucre ; leaves entire, in whorls or all basal, 

 rarely alternate Polygonaceae, 76 



