CACTACEX, 569 
with a 3—4-cleft calyx. Stamens 3—7; anthers 2-celled, linear, 
bursting longitudinally. Female flower with a superior 35—4- 
toothed calyx, and a 1-celled ovary, with 3—4 polyspermous 
parietal placentas. Fru't dry, opening at the apex. Seeds 
without albumen, minute, numerous. This order is commonly 
placed among the Monochlamydex ; but its affinities are clearly 
with Begoniacex and Cucurbitacex, and hence it is placed here. 
Distribution and Numbers.—They are widely distributed over 
the globe. Illustrative Genera :—Datisca, Linn.; Tetrameles, 
R. Br. The above are the only genera: there are 4 species. 
Properties and Uses.—Of little importance. Useful fibres 
might probably be obtained from the plants of this order. 
Datisca cannabina is bitter and purgative. The root is employed in 
Cashmere as a yellow dye. 
Cohort 4. Ficoidales.—Stamens generally numerous, epigynous 
or perigynous. Gyncecium syncarpous ; ovary 1- or many- 
celled. Seeds albuminous or exalbuminons. Leaves simple 
when present, and exstipulate. Stem usually fleshy. 
Order 1. CactacE#, the Cactus Order.—Character.—Suc- 
eulent plants, which are usually spiny and leafless. Stems fleshy, 
globular, columnar, flattened, or 3- or more angled, and alto- 
Fig. 966. Fie. 967. 
Fig. 966. Vertical section of 
the flower of the Prickly 
Pear (Opuntia vulgaris). 
——Fig. 967. Diagram of 
the flower of the same. 
gether presenting a peculiar and irregular appearance. Flowers 
solitary, sessile. Sepals and petals imbricate, usually numerous, 
in several whorls (jig. 967), and scarcely distinguishable from 
each other, or rarely 4-merous ; adherent to the ovary (jig. 966). 
Stamens numerous (figs. 966 and 967), with long filaments and 
versatile anthers, Ovary inferior (fig. 966), fleshy, 1-celled, with 
