DICTTOGEN^. 665 



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

 commerce, all the sago imported into Europe being deriyed from species 

 of Palms. (See Sagus and Saguerus.) Japan sago and other kinds are 

 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 arro^\Toot. 



Encephalarios.—Yaxioxis species contain starch, and form what is called 

 Caffre- bread. 



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

 arrowroot is prepared from the starch obtained from the stems of Z. inte^ 

 grifolia 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. 



Artificial Analysis of the Natural Orders of the Gtuxospermia. 

 Class I. Bicotyledones. 

 Division 2. Gymnosper mi a. 



1. Stem jointed, branched Gnetacece. 240. 



2. Stem not jointed. 



Branched, Leaves simple. 



Carpels collected in cones .... Coniferce. 238. 



Seed soUtai-y, suiTounded by scales . . . Taxacece. 239. 



Not branched. Leaves pinnate .... Cycadacece. 241. 



Class II.— MONOCOTYLEDONES. 



Sub-class I. LidyogencB. 



Natural Order 242, Dioscoeeaceje. — The Yam Order, — 

 Character, — Shrubby plants, vith twining stems rising from 

 tuberous root-stocks or tubers placed above or under the 

 ground. Leaves net-veined, stalked, Floicers unisexual, dioe- 

 cious, small, bracteated, arranged in a spiked manner, Male 

 fower : — Ferianth 6-cleft, Stamens 6, inserted at the base of 

 the perianth. Female flower: — Ferianth superior, 6-parted, 

 Ovary inferior, 3-celled ; styles 3, distinct, or 1 and then deeply 

 trifid ; ovules 1 — 2 in each cell, suspended. Fruit dehiscent 

 and compressed, or fleshy, 1 — 3-celled, Seeds albuminous ; 

 embryo small, in a cavity in the albumen, 



JDistrihution, ^r. — Chiefly tropical plants. Tamv.s communis 

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

 Exaynfles of the Genera: — Tamus, Dioscorea. There are above 

 150 species. 



Fropcrties and Uses. — The plants generally contain an acrid 

 principle. The tuberous root-stocks of many species of Dioscorea 

 are, however, when boiled, used for food in tropical countrips. 



Dioscorea. — The tuberous root-stocks of several species, as those of D. 

 alata, D. sativa, and D. aculeaia, when boiled, are eaten in tropical countries, 

 as potatoes are in Europe, The Chinese Yam {D. Batatas) is now cultivated 

 in this country, and when properly boiled is much esteemed by many as an 



