28 Key to the Families 



DICOTYLEDONEAE 



T. Corolla none; calyx present or lacking U. 



U. Flowers monoecious or dioecious (rarely polygamous), one or both sorts in 

 catkins or dense heads V. 

 V. Staminate or pistillate (not both) flowers in catkins or catkinlike heads. 

 Pistillate flowers in a short catkin or catkinlike head. . . .64. Moraceae, p. 394. 

 Pistillate flowers single or clustered; the staminate in slender catkins (except 

 in Fagus) . 

 Leaves pinnate; pistillate flowers and fruit naked. .60. Juglandaceae, p. 365. 



Leaves simple; pistillate flowers 1-3 in a cup or involucre 



62. Fagaceae, p. 378. 



V. Staminate and pistillate (both) flowers in catkins or catkinlike heads W. 

 W. Ovary many-ovuled; fruit many-seeded. 



Ovary and pod 2-celled; seed not tufted 3298. Liquidambar, p. 523. 



Ovary and pod 1-celled; seeds hairy-tufted 56. Salicaceae, p. 352. 



W. Ovary 1- or 2-celled; cells 1-ovuled; fruit 1-seeded. 



Parasitic on trees; fruit a berry 67. Loranthaceae, p. 402. 



Trees and shrubs, not parasitic. 



Calyx regular in fertile flower, succulent in fruit. . . .64. Moraceae, p. 394. 

 Calyx none or rudimentary and scalelike. 



Style and stigma simple ; leaves palmately angled or lobed 



124. Platanaceae, p. 523. 



Styles or long stigmas 2. 



Pistillate flowers 2 or 3 at each scale of the catkin 



61. Betulaceae, p. 373. 



Pistillate flowers single under each scale; nutlets naked, drupelike 



57. Myricaceae, p. 365. 



U. Flowers not in catkins X. 



X. Ovary or its cells containing only 1 or 2 (rarely 3 or 4) ovules Y. 

 Y. Pistil composed of more than one carpel; carpels distinct or nearly so. 



Stamens insterted on the calyx; leaves with stipules. .126. Rosaceae, p. 524. 

 Stamens inserted on the receptacle. 



Leaves punctate with transparent glands 3990. Zanthoxylum, p. 632. 



Leaves not punctate with glands. 



Calyx present, usually colored or petal-like 



91. Ranunculaceae, p. 454. 



Calyx none; flowers in a spike 52. Saururaceae, p. 352. 



Y. Pistil simple or compound but without distinct carpels Z. 

 Z. Ovary free from the calyx, which is sometimes lacking a. 

 a. Stipules (ocreae) sheathing the stem at the nodes. 



Calyx none ; trees 124. Platanaceae, p. 523. 



Calyx present, commonly petal-like; herbs. .77. Polygonaceae, p. 405. 

 a. Stipules not sheathing the stem or lacking b. 

 b. Herbs c. 



c. Plants aquatic, submerged or nearly so. 



Leaves whorled, dissected; style 1...89. Ceratophyllaceae, p. 4:">4. 



Leaves opposite, entire; styles 2; ovary 4-celled 



148. Callitrichaceae, p. 646. 



c. Plants not aquatic d. 



d. Styles 10; ovary and berry 10-celled. .83. Phytolaccaceae, p. 433. 

 d. Style, if any, and stigma 1. 



Flowers unisexual; ovary of the fertile flowers 1-celled 



65. Urticaceae, p. 397. 



Flowers perfect; pods 2-celled, 2-seeded 



2883. Lepidum, p. 487. 



