THE DICOTYLEDONES 



1719 



though M. spinosiim develops thorns. Some Hke M. crystallimim are covered 

 with gHstening bladder-shaped hairs which earn that species the name of Ice 

 Plant. It is widely distributed in South Africa, as well as in California, 

 South and Western Australia and in the Mediterranean region. M. edule 

 is interesting; it is a South African species which has become naturalized 

 in Britain, occurring on the rocks by the seashore in the Isle of Wight, 

 Cornwall and the Channel Islands. The fruits, which are capsules, contain 

 a sweet pulp and are eaten in South Africa under the name of Hottentot 

 Figs. The perianth in Mesembryanthemiim consists of four sepaloid seg- 

 ments. The numerous apparent petals are really staminodes. 



The Nyctaginaceae are placed by Hutchinson in his Thymelaeales. 

 They are mostly shrubs or trees with flowers in cymose inflorescences 

 surrounded by brightly coloured bracts: the calyx is tubular and often 

 petaloid. They occur chiefly in tropical and temperate America. The 

 best known is Boiigainvillea spectabilis (Fig. 1594) which is a climbing, 



Fig. 1594. — Boiigainvillea spectabilis. A, Single flower, adnate at the base to the 

 large coloured bract, which serves as a wing for wind dispersal of the fruit. 

 B, Three-flowered inflorescence with bracts. C, Sexual organs from a 

 young flower. (After Baillon.) 



shrubby plant, native of Brazil. In this country it is often grown in green- 

 houses but in warmer countries it forms one of the most characteristic out- 

 door climbers, being cultivated wherever white settlements have been 

 established. The brilliant purple or reddish bracts make the flower spikes 

 extremely striking despite the fact that the flowers themselves are incon- 

 spicuous. The stem structure is anomalous, the cambium developing out- 

 side the original ring of vascular bundles. From it new closed bundles as 

 well as intermediate xylem are formed; the phloem in these new bundles 

 however is verv poorly developed. Another important genus is Mirabilis. 

 M. jalapa (the Marvel of Peru) is a well-known ornamental plant with 

 tuberous roots and a fleshy stem 2 ft. to 3 ft. high. The flowers are tubular 



