KEY TO NATURAL ORDERS. 23 



B. FLOWERS, OXE OR BOTH SORTS, IN AMENTS OR CATKIX-LIKE HEADS. 



Twining dioecious herbs ; fertile flowers only in PAGE. 



short aments. Humulus in URTICACE.E, 291 



Shrubby plants, parasitic on trees. Fruit a berry. LORANTHACE^E, 286 

 Trees or shrubs. 



Sterile flowers only in aments. Flowers 

 monoecious. 



Leaves pinnate. Ovary and fruit with- 

 out an involucre. JUGLANDACILE, 302 

 Leaves simple. Nuts one or more in a 



cup or involucre. CUPULIFERE, 307 



Flowers of both kinds in aments or close 

 heads. 

 Leaves palmately-veined or lobed. 



Calyx 4-cleft, in the fertile flowers 



becoming berry-like. Morus in URTICACE.E, 291 



Calyx none : flowers in round heads. PLATANACE^E, 301 



Leaves pinnately-veined. 



Flowers dioecious, 1 on each scale. 



Pod many-seeded. SALICACE^E, 328 



Flowers monoecious, the fertile ones 



2 or more under each scale. BETULACE^E, 824 



Flowers only 1 under each fertile 



scale. 

 Fruit 1 -seeded. MYRICACE.E, 323 



SUB-CLASS 2. GYMKOSPERMS. Pistil represented by an open scale or leaf, 

 or sometimes entirely wanting ; the ovules and seeds naked. 

 Flowers monoecious or dioecious. Stems 



branched. Leaves simple. CONIFERS, 333 



