FAMILIES OF FLOWERING PLANTS. 



57 



Family Taccaceae. Tacca Family. The type and only important 

 o-enus of this small family furnishes the pia plant, {Tacca pimiatijida) 

 an herb extensively cultivated throughout the East Indies and Poly- 

 nesia as a source of arrowroot. The plauts of the family are all 

 tropical her])s, with thick roots and basal leaves, the flowers usually 

 small, and borne in umbellate clusters. 



Yio. 49.— The wild yam, Dioscorfa riUosa. showing flowers and fruit. Original. 



Family Dioscoreaceae. Yam family. Contains about 9 genera 

 and nearly 200 species, chiefly natives of tropical America. They are 

 herbaceous or woody twining vines, the leaves mostly alternate and 

 netted-veined, the flowers dioecious or monoecious, small and incon- 

 spicuous, in axillary clusters. The fruit in Dioseorea, the type genus 



