374 



MANUAL OF POISONOUS PLANTS 



gravelly soils, has mucilaginous stems, blue ephemeral flowers, and is common 

 everywhere in eastern North America. Several species of Tradescantia, like 

 the wandering Jew (T. Zebrina), are commonly cultivated. Another family 

 of the order is the Pontederiaceae, containing the pickerel weed (Pontederia 

 cordata) and the Eichornia speciosa, which is frequently cultivated in green- 

 hoses and has become a very troublesome weed in the rivers of Florida and 

 elsewhere in warm countries. 



LILIIFLORAE 



Herbs or occasionally shrubs with endogenous stems and monocotyledon- 

 ous seeds ; perianth generally well developed ; flowers generally regular and 

 complete, their parts in 3's and 6's; ovary superior, or inferior compound; 

 endosperm horny or fleshy. This series contains the family Juncaceae, called 



rushes, some of which, 

 like wire-grass (Juncus 

 tennis), are troublesome 

 weeds. Lusula is com- 

 mon at high altitudes 

 and in northern states. 

 The Dioscoreaceae, or 

 Yam Famuly, contains 

 but few species in the 

 United States. To this 

 belong the wild yam 

 root {Dioscorea villosa) 

 of our woods, the Jap- 

 anese yam. (D. divari- 

 cata) and the air po- 

 tato (D. bulbifera) of 

 Asia, sometimes culti- 

 vated in the Gulf States 

 for its large tubers. 

 Yam starch is obtained 

 from several species, the 

 most important of which 

 are D. alata, D. sativa, 

 D. japonica, and D. 

 aculeata. 



The family Taccaceae 

 contains Tacca pinnati- 



_,, i f ... r IT fida, the roots of which 



Fig. 160. Flowers, fruit and leaves of Yam (Dioscorea' 



villosa). A common plant in thickets. are the source of the 



Tacca starch of Tahiti 

 and the neighboring islands. The plant is grown also in Brazil and India. 



FAMILIES OF LILIIFLORAE 



Ovary mostly superior. 



Perianth segments distinct or partly united, the inner, petal-like ; 



fruit a capsule or berry Liliaceae 



