CACTIFLORjE. 



375 



inflorescences are dichasia and unipared scorpioid cymes. Aizoon, Mollugo, 

 Sesuvium, and others are herbs or bushes, most frequently hairy. 



2. MESEMBBIANTHEME;E have semi- or wholly-epigynous flowers. Tetra- 

 gonia. The perianth is 4 (more rarely 3-5-6) -merous. Stamens single, or (by 

 splitting) in groups alternating with the perianth- leaves. There is an indefinite 

 number of carpels, and each loculus of the ovary contains only 1 pendulous 

 ovule. Fruit a nut or drupe. The flowers arise singly in the leaf-axils, with an 

 accessory foliage-bud below them ; in some instances there is also an accessory 

 flower between this bud and the flower. Southern hemisphere, especially at 

 the Cape ; T. expansa, New Zealand Spinach, is a fleshy plant which is 

 cultivated as a pot-herb (Japan, Austr., S. Am.). Mesembrianthemum : the 

 flowers are 5-merous; the numerous linear petals and the still more nu- 

 merous stamens all arise by the splitting of 5 or 4 protuberances (primordia) 

 alternating with the sepals. The ovary presents another characteristic peculi- 

 arity : the carpels alternating with the 5-4 stamens form an ovary (with several 

 loculi) with the ovules at first borne, as in other cases, on the inner corner 

 of the inwardly-turned carpels; but during the subsequent development the 

 whole ovary is so turned round that the placentae become parietal and the 

 ovules assume, apparently, a position very rarely met with in the vegetable 

 kingdom : on the dorsal suture of the carpels. Shrubs or under-shrubs, more 

 rarely herbs with fleshy stems and simple, entire, more frequently thick or 

 triangular leaves, containing a quantity of water. The flowers open about noon, 

 and are brightly coloui'ed, generally red or red-violet, but odourless. The 

 capsules dehisce in rainy weather. 300 species, mostly found at the Cape. 

 Some are ornamental plants. M. crystallinum (the Ice-plant) and others are 

 covered with peculiar, bladder-like, sparkling hairs, the cell-sap of which con- 

 tains salt these serve as reservoirs of water. 



Family 8. Cactiflorae. 



The position of this family is very doubtful ; but it seems in 

 many respects to approach Mesembrianthemum. Some botanists 

 place it near to the Ribesiaceae ; others, again, to the Passifloraceas. 

 Only 1 order. 



Order Cactacese (The Cacti). The flower is epigynous, , 

 regular, and remarkable for its acyclic structure; there are, for 

 instance, a large number of spirally- placed sepals and petals, which 

 gradually pass over into one another, and which in some species, to 

 a certain extent, arise from the walls of the ovary as in Nymphsea 

 (Fig. 383 A, B}. The petals are free; rotate, opening widely in 

 Opuntia, Pereskia, and Ithipsalis ; erect and united at their base 

 into a Shorter or longer tube in Cereus, Epiphyllum, Mammillaria, 

 Echinocactus, Melocactus, and others (Fig. 369). Stamens numerous, 

 attached to the base of the corolla ; gynceceum formed of many 

 carpels, with one style, dividing into a number of branches corres- 

 ponding to the number of carpels ; the ovary has one loculus with 



