24 Karl M. Wiegand and Arthur J. Eames 



KEY TO THE FAMILIES OF ANGIOSPERMS CONTAINING DIOECIOUS 



SPECIES 



PAGE 



(7. Woody plants. 

 b. Leaves opposite. 



c. Plants scurfy, covered with silvery or brown peltate scales ; leaves simple. 



Elaeagnaceae 311 

 c . Plants not peltate-scurfy ; leaves compound. 

 d. Leaflets 3, rarely 5; stamens 5-10; calyx S-parted; wing of fruit 



unsymmetrical Aceraceae 293 



d. Leaflets 5-11 ; stamens 2 (4) ; calyx 4-parted ; wing of fruit symmetrical. 



Fraxinus 340 

 b. Leaves alternate. 



c. Stem twining or recurved and brier-like. 



d. Flowers umbellate; stems usually prickly; monocotyledons Smilax 149 



</. Flower paniculate; stems not prickly; dicotyledons .... Menispermaceae 218 

 c. Stems neither twining nor brier-like. 



d. Flowers in catkins or short spikes, or often in peduncled subpaniculate 

 heads. 

 c. Perianth 4-5-parted or differentiated into calyx and corolla, not glandu- 

 lar; bud scales several. 



/. Pith of twigs continuous Urticaceae 180 



/. Pith of twigs with woody diaphragms Nyssa 329 



c. Perianth finger-like or cup-shaped, glandular, not parted ; bud scale 1 



or several (see also 3d e) Salicaceae 161 



e. Perianth none ; bud scales several Myricaceae 171 



</. Flowers not in catkins or short spikes. 

 c. Leaves pinnately compound. 



/. Leaflets dotted, crenulate or entire ; shrubs ; twigs dark, prickly. 



Zanthoxylum 286 

 /. Leaflets not dotted, with a few coarse basal teeth ; trees ; twigs pale, 



not prickly Simarubaceae 286 



c. Leaves simple. 



/. Leaves serrate-dentate ; twigs not spicy Urticaceae 180 



/. Leaves entire or lobed : twigs spicy Lauraceae 219 



a. Herbs. 



b. Flowers in involucrate heads Compositae 394 



b. Flowers not in involucrate heads. 

 c. Plants aquatic, submerged, flaccid. 



d. Leaves opposite, cauline Najadaceae 46 



d. Leaves whorled and cauline, or basal Hydrocharitaceae 54 



c. Plants not as above. 



d. Flowers with both calyx and corolla. 

 e. Leaves simple. 



/. Corolla of 3 petals ; erect herbs Alismaceae 53 



/. Corolla deeply 5-parted, or petals 5 ; vines Cucurbitaceae 392 



c. Leaves compound ; corolla of 5 petals ; erect herbs Panax 319 



d. Flowers apetalous or perianth parts all similar (see also Panax). 



e. Flowers umbellate; plants with tendrils and recurved stems Smilax 149 



e. Flowers not umbellate. 



/. Flowers on a spadix inclosed in a spathe Araceae 134 



/. Flowers not as above. 



g. Leaves ternately decompound Thalictrum 214 



g. Leaves simple. 



h. Leaves with sheathing scarious stipules Polygonaceae 185 



