66 KEY AND FLORA 



4-cleft calyx, 4 stamens, and a rudimentary ovary; pistil- 

 late flowers in capitate clusters, calyx 3-4-toothed. Ovary 

 stalked; style 2-cleft. Fruit in a globular head.* 



1. B. papyrifera Vent. PAPER MULBERRY. A round-topped tree 

 with yellowish-brown bark. Leaves cordate, often irregularly 2-3- 

 lobed, serrate, rough above, downy beneath, long-petioled. Staminate 

 spikelets peduncled, 2-3 in. long. Pistillate heads stout, peduncled, 

 about 1 in. in diameter. Introduced from Asia and very common S. 

 about old dooryards.* 



IV. CANNABIS L. 



Coarse herbs with very tough, fibrous bark. Leaves usu- 

 ally opposite, palmately compound. Flowers small, dioecious, 

 greenish, the staminate ones in compoiind racemes or panicles, 

 the pistillate ones in spikes. Calyx of the staminate flowers of 

 5 sepals, that of the pistillate flowers of 1 large sepal which 

 covers the ovary and the akene. 



1. C. sativa L. COMMON HEMP. An erect plant, 4-8 ft. high. 

 Leaves large, petioled, of 5-7 lanceolate, irregularly serrate or toothed 

 leaflets. Cultivated from Europe, S. and W., for its fiber, and some- 

 times runs wild along roadsides in rich soil. 



21. URTICACE-ffi. NETTLE FAMILY 



Herbs with watery juice, stem and leaves often clothed with 

 stinging hairs. Leaves undivided, stipulate. Flowers small, 

 greenish, unisexual, apetalous in axillary clusters. Calyx of 

 the staminate flowers 4-5-parted or 4-5-sepalous ; stamens as 

 many as the sepals and opposite them ; filaments inflexed in 

 the bud and straightening at maturity ; anthers 2-celled. Calyx 

 of pistillate flowers 2-4-sepalous ; ovary sessile, 1-celled ; 

 stigma simple or tufted. Fruit an akene commonly inclosed 

 in' the dry, persistent calyx.* 



URTICA L. 



Annual or perennial herbs. Leaves with stinging hairs, 

 opposite, petioled, several-nerved, dentate or incised, stipulate. 

 Flowers monoecious or dioecious. Calyx of the staminate 



