168 SOUTH AFRICAN BOTANY 
Calyx.—2+2, inferior, polysepalous, the 2 lateral 
sepals pouched. 
Corolla.—4, inferior, polypetalous, cruciform—petals 
clawed. 
Androecium.—2 + 4, tetradynamous, inferior, nectaries 
at base of two short lateral stamens, anthers dorsifixed, 
introrse. 
Gynoecium.—Syncarpous 2, superior, ovary bilocular, 
owing to the development of a false septum between 
the two parietal placentas. Ovules numerous. 
Fruit.—A siliqua. 
Pollination.—The calyx forms a kind of tube holding 
the petals together and thus the honey is partially con- 
cealed. The flowers are attractive to insects, but there 
is no special device for ensuring cross-pollination, hence 
self pollination is probably quite frequent. 
Other Genera. — Heliophila is common in South 
Africa; it has blue flowers. Brassica is a large genus, 
extensively cultivated; it includes Cabbage, Turnip 
and Mustard. Matthiola (the Stock) is cultivated for its 
flowers. Iberis (Candytuft) has irregular flowers, the 
two outer petals of each flower being much larger than 
the other two; it has a silicula for its fruit. Capsella 
(Shepherd’s Purse) is a fairly common weed ;—-Nastur- 
tium (Watercress), Lepidium (Cress), Cochlearia (Horse 
Radish), and Raphanus (Radish) are all used as veget- 
ables. 
149. N. O. Crassulaceae.— General Characters, ~— 
Plants, usually perennials, with xerophytic characters, 
e.g. fleshy leaves and stems, tufted growth, close pack- 
