662 SYSTEMATIC BOTANY. 



Cape of Good Hope, Madagascar, and Australia. Examples : — 

 Cycas, Dion, Zamia, Encephalartos. Tliere are 7 genera, and 

 46 species. 



Properties and Uses. — The stems and seeds of the plants of 

 this order yield mucilage and starch. 



Ci/cas.— From the stems of Ci/cas circinalis and C revoluta, a starch may 

 be obtained. Of this a kind of sago is prepared ; that from C. revoluta is 

 said to constitute Japan Sago. This sago is not an article of European com- 

 merce, all the sago imported into Europe being derived from species of Palms. 

 (See Sagus and Saguerus.) Japan sago and other kinds are much esteemed 

 as articles of food. The seeds of the above species are also edible. 



Dion edule has large mealy seeds from which the Mexicans prepare a kind 

 of arrow-root. 



Zamia.— In the Bahamas and other West Indian Islands, excellent arrow- 

 root is prepared from the starch obtained from the stems of Z. integrifolia and 

 other species. It is sold in the West India markets, but is not known as a 

 commercial article in this country or in any other part of Europe. 



Encephalartos Various species contain starch, and form what is called 



Caffre-bread. 



Artificial Analysis of the Natural Orders of the GrMNOSPERMiA. 



Class I. Dicotyledones. 

 Division 2. Gymnospermia. 



1 . Stem jointed, branched. 



Anthers 1 -celled with porous dehiscence . . GnetacecE.2iQ. 



2. Stem not jointed. 



Branched. Leaves simple. 



Seeds in cones Coniferce. 238. 



Seeds solitary Taxacece. 239. 



Not branched. Leaves pinnate .... Cycadacecs. 241. 



Class II. MONOCOTYLEDONES. 

 Sub-class L Dictijogence. 



Natural Order 242. DioscoREACEiE. — The Yam Order. — 

 Shrubby plants, with twining stems rising from tuberous 

 root-stocks or tubers placed above or under the ground. 

 Leaves net-veined, stalked. Flowers unisexual, dioecious, small, 

 bractcated, arranged in a spiked manner. Malcjlower : — Perianth 

 6-cleft. Stamens 6, inserted at the base of the perianth. Female 

 flower : — Perianth superior, 6-parted. Ovary inferior, 3-celled ; 

 styles 3, distinct, or 1 and deeply trifid; ovules 1 — 2 in each cell, 

 suspended. Fruit dehiscent and compressed, or fleshy, 1 — 3- 

 ccUcd. Seeds albuminous ; embryo small, in a cavity in the 

 albumen. 



Distribution, Sfc. — Chiefly tropical plants. Tamus communis 

 is, however, found in Britain and other temperate regions. 

 Examples : — Tamus, Testudinaria, Dioscorea. There arc 7 

 genera, and 1 50 species. 



Properties and Uses. — The plants generally contain an acrid 



