Jio DIOSCOREACEM. [chap. 



compared with the minute representatives of the Family in 

 Europe, belonging to the genus Duckweed {Lemna). Their 

 fronds are everywhere common, floating in stagnant water. 

 Some species of Lemna occur in India. 



ICO. Natural Order, TaccacecB. — The Tacca Family. 



Herbs, with radical leaves and scapes, bearing umbellate 



flowers. 



Type — Tacca pinnatifida. 



A perennial herb, cultivated in Southern India, with 

 large, tripartite, radical leaves with pinnatifid lobes, and 

 long scapes bearing an involucrate umbel of greenish flowers. 



This species is cultivated all through Polynesia for the 

 sake of its mealy tubers. The Family is a very small one, 

 and co'-'iined to the tropics of the Old World. 



PETALOIDEiE. 



Id. Natural Order, Dioscoreacece. — The Yam Family. 



Usually twining herbs, with net-veined, simple or digitate 

 leaves. Flowers unisexual. Perianth six-lobed. Ovary 

 inferior, three-celled. 



Type — Dioscorea sativa (or any other species of Yam). 



A twining herb, with alternate, more or less cordate 

 leaves, axillary spikes of very small dioecious flowers ; the 



