VI 



General Key to the Families 



Staminate flowers in catkins; pistillate 

 flowers subtended by an involucre which 

 becomes a bur or a cup in fruit. 

 Flowers not in catkins (in catkin-like spikes 

 in the Mulberries); variously clustered or 

 rarely solitary. 

 Ovary superior, free from the calyx; flowers 

 mostly imperfect. 

 Stamens not adnate to the calyx; flowers 

 regular. 

 Sap not milky. 

 Sap milky. 

 Stamens adnate to the calyx; flowers ir- 

 regular. 

 Ovary inferior, at least in part, adnate to the 



calyx. 

 Ovary superior; flowers perfect, regular. 

 Stipules united into a sheath. 

 Stipules none, 

 b. Petals present (wanting in the Laurel 

 Family; in the Sweet Gum; in some 

 Prickly Ashes; in the Spurge Family; in 

 some Maples, and in some of the Buck- 

 thorn Family, the Chocolate Family and 

 the Hand Tree Family). 

 * Ovary superior, free from the calyx (ex- 

 cept in the Witch Hazel and Apple Families). 

 t Ovary or ovaries simple; sepals mostly separate. 

 Stamens numerous; petals present. 

 Fruit aggregate, cone-like. 

 Fruit large berries. 

 Stamens 9 or 12, in 3 or 4 series of 3; petals none 

 It Ovary compound; sepals separate; 

 stamens hypogj^nous. 

 Leaves simple. 

 Leaves pinnately decompound. 



ttfOvary simple or compound; sepals 

 confluent with the concave receptacle 

 (hypanthium); stamens epig}^nous or 

 perigynous. 

 JFlowers regular or nearly so. 

 Endosperm of the seed usually copious. 

 Leaves opposite. 

 Leaves alternate. 



Corolla and usually the calyx present; 



ovule one. 

 Corolla and calyx wanting; ovules many; 

 flowers in dense heads. 

 Endosperm none. 



Flowers monoecious, minute, in dense heads. 



Beech Family. 



PAGE 



268 



Magnolia FAinLY. 

 Custard -Apple Family. 

 Laurel Family. 



Caper Family. 

 Horseradish Tree Faivuly. 



384 

 394 

 397 



405 



407 



Cunonia Family. 408 



Witch Hazel Family. 410 



Sweet Gum Family. 412 



Plane Tree Family. 415 



