KEY TO THE ORDERS. 
xix 
Stamens inserted below the ovary. 
Families in Order 25. Ranales. 
Stamens inserted on the edge of a cup-shaped hypanthium. 
Families in Order 27. Rosales. 
Gynoecium of 2 or several united carpels; stigmas or styles 2 or 
several. 
Ovary, by abortion, i-celled and i-ovuled. 
Leaves with sheathing stipules (ocreae). 
Order 23. Polygonales. 
Leaves estipulate, or if stipules are present they are not 
sheathing. 
Trees or shrubs; ovary not seated in a hypanthium. 
Ulmaceas in Order 21. Urticales. 
Herbs or vines. 
Stipules herbaceous: inflorescence spicate or racemose: 
leaf-blades palmately veined. 
Cannabinaceae in Order 21. Urticales. 
Stipules scarious or hyaline or none; inflorescence cy- 
mose: leaf-blades pinnately veined. 
Families in Order 24. Chenopodiales. 
Ovary several-celled, or with several placentae, several-ovuled. 
Stamens hypogynous, inserted under the gynoecium in the per¬ 
fect flowers, not on a disk in the pistillate flowers. 
Flowers perfect. 
Stamens not tetradynamous. 
Stamens 2; inflorescence spicate. 
Besseya in Order 44. Polemoniales. 
Stamens 3-10; inflorescence cymose. 
Order 24. Chenopodiales. 
Stamens tetradynamous. 
Brassicaceae in Order 26. Papaverales. 
Flowers monoecious or dioecious. 
Euphorbiaceae in Order 30. Euphorbiales. 
Stamens perigynous or epigynous, inserted on the margin of a 
hypanthium or a disk. 
Fruit a samara. Aceraceae in Order 31. Sapindales. 
Fruit drupe-like or berry-like. Order 32. Rhamnales. 
b. Ovary inferior. 
Flowers not in involucrate heads. 
Fruit a berry or a drupe, or nut-like. 
Stamens as many as the perianth-members and alternate with 
them, or fewer. 
Tetragoniaceae in Order 24. Chenopodiales. 
Stamens as many as the perianth-members and opposite them, 
or twice as many. Families in Order 37. Myrtales. 
Fruit a capsule. 
Sepals as many as the ovary-cavities or one-half as many. 
Order 37. Myrtales. 
Sepals (4-5) at least twice as many as the ovary-cavities. 
Styles 2-3 ; leaves alternate. 
Saxifragaceas in Order 27. Rosales. 
Styles solitary; leaves opposite. 
Glaux in Order 40. Primulales. 
Flowers, at least the staminate, in involucrate heads. 
Ambrosiaceae in Order 49. Carduales. 
B. Corolla present. 
I. Petals distinct, at least at the base. 
1. Carpels solitary, or several and distinct, or united only at the base. 
Stamens at the base of the receptacle, i. e., hypogynous. 
134 
169 
101 
100 
100 
113 
313 
11 3 
150 
222 
226 
227 
124 
240 
240 
170 
264 
327 
