GRAMINACE^E. 



659 



Order 117.— DIOSCOREACEiE.— IAndley. 



Flowers dioecious. Calyx and corolla alike, herbaceous. Sterile flowers : stamens 6, 

 inserted on base of perianth, anthers introrse, with a longitudinal dehiscence. Fertile 

 flowers : ovary adherent, 3-celled, with the cells 1 — 2-seeded ; styles deeply trifid ; stig- 

 mas undivided; ovules suspended, anatropal. Fruit leafy, compressed, with 2 of the 

 cells often abortive ; sometimes succulent. Seeds 2 in each cell, or by abortion 1, com- 

 pressed, winged or wingless; embryo small, in a large cavity of cartilaginous albumen. 



These are twining shrubs, often with large tubers, and alternate, occasion- 

 ally opposite leaves, having reticulated veins. The flowers are small and 

 bracteate. It is not a very extensive order, of principally tropical species, 

 many of which have acrid roots, whilst in others this part is farinaceous and 

 nutritive. That of Tamus communis, or Black Bryony, is active, and was 

 formerly employed, in a bruised state, as a stimulating poultice, and as an 

 application to contusions, to promote the absorption of coagulated blood. It 

 was also administered, in small doses, as a diuretic. The young shoots, how- 

 ever, are eaten by the Arabs when in a raw state, and Matthiolus states that 

 they were sold in Italy as a substitute for asparagus [Comment, on Dioscor. 

 467). Those of T. cretica are used in the same way in Greece, but End- 

 licher observes that except they are well boiled, they are eminently purga- 

 tive and even emetic. Some species of Dioscorea have very acrid tubers ,* 

 thus those of D. triphylla and D. dcemona are excessively nauseous even 

 after being cooked ; on the other hand, in many of them this is bland and 

 edible, and is known under the name of Yam. Those most generally cultivated 

 are, D. alata, in the East and West Indies ; D. but- 

 bifera in Tahiti and the Moluccas ; D.japonica, in 

 Japan ; and there is a species in Congo, which is said 

 to be so acrid, as to require to be boiled for four days 

 to render it edible. One of our native species, the 

 D. villosa, or Wild Yam, has a woody and con- 

 torted root, which, according to Riddell (Synop. 

 Flor. West. St. 93), is possessed of valuable medi- 

 cal properties. He states that a decoction of it is 

 eminently beneficial in bilious colic. This is made 

 with an ounce of the root in a pint of water, of 

 which half is to be administered at a time. He adds 

 that it acts with great promptitude, and' that he has 

 been informed that Dr. Neville places much reliance 

 on the tincture as an expectorant, and also that it 

 acts as a diaphoretic, and in large doses as an 

 emetic. 



Fig. 311. 



D. alata. 



Group LI. — Glumales. 



Order 118.— GRAMINACE^.— Lindley. 



Flowers usually perfect, sometimes monoecious or polygamous ; consisting of imbri- 

 cated bracts, of which the most exterior are called glumes ; the central enclosing the sta- 

 mens, paleae ; and the internal at the base of the ovary, scales. Glumes mostly 2, alter- 

 nate ; sometimes single, usually unequal. Paleae 2, alternate ; the exterior or lower, 

 simple, the upper or interior composed of 2 united by their contiguous margins, and ge- 



