Succulent cacti

More than 95% of the plants of the world follow the C3path, whereby the carbon dioxide is initially incorporated, by the plants, into intermediate compounds made up of three atoms of carbon - which is the reason these plants are known as C3 plants. Only about 1% of all plants, including maize, millet, sorghum, and sugarcane, follow the C4 path, incorporating carbon dioxide into intermediate compounds made up of four atoms of carbon - which is the reason these plants are known as C4 plants. The remaining 4% of plants, mostly succulents (cacti), follow the third, CAM, path, which has no bearing on the discussion that follows. 

Meyer BN and McLaughlin JL. 1981. Economic uses of Opuntia. Cactus Succulent J 53 107—112. 

The first peyote to be scientifically examined came to the laboratory in Germany in dried form. When dried, the succulent part of the cactus shrivels greatly, while the center tufts remain much the same. Boiling the specimens only partially restored their original appearance, as indicated by this drawing from 1888. 

Figure 7-13. Temperatures at the soil surface and at a depth of 0.10 m for a hot summer day in the northwestern Sonoran Desert. The maximum air temperature at 1.5 m above the ground was 34°C on a clear day with low wind speeds. A depth of 0.10 m is near the center of the root zone for two locally common perennial succulents, the desert agave Agave deserti and the barrel cactus Ferocactus acanthodes, both of whose roots are excluded from the upper 0.03 m of the soil due to the high temperatures there (Nobel, 1988).

XX. Order Opuntiales.—Cactacea or Cactus Family.—Herbaceous rarely arborescent Cereus giganteus) more or less succulent... 

Ostolaza, C.N. et al. 1985. Neoraimondia arequipensisysi. rosefbsra ( Jfferd. Back-eb.)Eauh. Cactus and Succulent Journal 57 60-64. 

Plants (e.g, cactus and other succulents) that, unlike the C3 and C4 plants, temporarily separate the processes of carbon dioxide uptake and fixation when grown under arid conditions. They take up gaseous carbon dioxide at night when the stomata are open and water loss is minimal. During the day when the stomata are closed, the stored C02 is released and chemically processed. When CAM plants are not under water stress, they then follow C3 photosynthesis. 

Cactus alkaloids. About 2000 cactus species (stem succulents) of tropical and subtropical desert areas are known, some of which contain h lucinogenic principles, e. g., Lophophora species indigenous to Mexico together with other hallucinogenic cacti the latter are known as peyote (see Lophophora alkaloids). They contain ca. 5% alkaloids such as mescaline, anhalo-nine, lophophorine, pellotine, etc., mainly isoquinoline alkaloids, and phenylethylamine alkaloids. 

The Euphorbiaceae are a large family of about 280 genera and some 7300 species (Lawrence, 1955). They can be either trees, shrubs, herbs, or vines and some are fleshily stemmed and cactus-like (Fig. 1.10). The major centers of distribution are tropical America and Africa. The succulent members are centered along both tropics in South America and Africa (Fig. 1.11) including the Canary Islands. 

Fig. 1.10. Euphorbia grandidens, a cactus-like succulent of Africa in the Euphorbiaceae which has been extensively studied as a CAM plant...

The great capacity for growth of certain succulents under favorable conditions is exemplified by the invasion and spread of cacti throughout a large area of Queensland and New South Wales, Australia between 1890 and 1920. Several species of Opuntia were introduced by sea captains and other visitors as curiosities and some Opuntia monocantha, for example, were intended for commercial purposes. Opuntia inermis (see Chap. 6.2.2.1 and Fig. 6.8) became the most serious pest (Fig. 6.13), but has largely been controlled by the moth Cactoblastus, Presently, Eriocereus, the Harissia Cactus, is a serious pest of valuable rangeland in Queensland (Fig. 6.14). 

Lyons (1974) Lyons, G. In Search of Dragons or The Plant that Roared Cactus Succulent Journal (U.S.) XLVI (1974) 267-282... 

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