CACALIA 



CACTUS 



203 



glabrous : Ivs. petioled. None of the species are known 

 to be in the Amer. trade, but some of the native kinds 

 may he expected to appear in commerce. For an account 

 of the N. Amer. species, see Gray, Syn. Fl., vol. 1, p. 2, 

 pp. 394-6. 



CACALIA of the florists. See Emilia. 



302. Showing the remarkable condensation of the plant 

 body in a cactus Mamillaria micromeris. 



CACALI6PSIS (Cacalia-like). Compdsitce. One spe- 

 cies, with discoid, very many-fld. heads of perfect yel- 

 low florets, and palmate Ivs. 



Nard6smia, Gray. Strong perennial, 1-2 ft. high, 

 loose, woolly, but becoming nearly glabrous : Ivs. nearly 

 all radical, long-stalked, 5-9-cleft or parted, the lobes 

 dentate or cut: heads an inch high, in a loose cluster 

 at the summit of the nearly naked stem, fragrant. Pine 

 woods, Calif, to Wash. Int. by Gillett in 1881 as a 

 border plant. 



CACAO, COCOA. See Theobroma. 



CACTUS, CACTI. The peculiar forms included under 

 this name constitute the family Cact&cece. They are 

 especially characteristic of the warm and dry regions of 

 America, their display being greatest in Mexico, although 

 extending from the plains of North America and east- 

 ward southward through the West Indies and Mexico to 

 southern South America. Aside from certain African 

 species of Rhipsalis, this great family, containing about 

 1,000 known species, is absolutely restricted to Amer- 

 ica. The common prickly pear (Opuntia Ficus-Indlca) 

 has long been naturalized throughout the Mediterranean 

 region, and its pulpy fruit is eaten under the name of 

 "Indian fig." The chief display of Cacti in the United 

 States is in the Mexican border states, representing 

 the northern edge of the still more extensive Mexican 

 display. 



The peculiar habit of the family seems to be the re- 

 sult of perennial drought conditions, to which they have 

 become remarkably adapted. The two-fold problem pre- 

 sented by such conditions is the storage of water and 

 the regulation of its loss. As a result of water storage, 

 the plant bodies are characteristically succulent. Loss 

 of water by transpiration is reduced to a minimum by 

 heavy epidermal walls and cuticle, and other anatomi- 

 cal devices, but perhaps still more by reducing the sur- 

 face exposure of the body in comparison with its mass 

 (Figs. 301, 302, 303). For the most part, foliage leaves 

 have been abandoned entirely, and their peculiar work 

 has been assumed by the superficial tissues of the stem. 

 The stem itself is flat or columnar or globular, the last 

 form representing the least exposure of surface in pro- 

 portion to the mass. The laterally developed leaves and 

 branches common to ordinary stems are generally re- 

 placed by various ephemeral or abortive structures, the 

 most notable of which are the bristles and remarkably 

 varied spines. The real nature of Cactus spines is a dis- 

 puted question, and not a very important one. When 

 rudimentary leaves appear, as in Opuntia, they are 

 found subtending the cushion or area in connection 

 with which the spines are developed. This area is 

 clearly an aborted branch, and the spines represent 



lateral members upon it ; and most probably these 

 lateral members represent leaves. The Cactus forms are 

 not always leafless or compact, for the species of Peres- 

 kia are climbing, woody forms, with well - developed 

 petiolate leaves (Fig. 309); and even the well-known 

 prickly pears (Opuntia) are more or less expanded, and 

 have very evident ephemeral leaves. 



The flowers are usually conspicuous, in many cases 

 remarkably large and brilliantly colored. The sepals 

 and petals are numerous, arranged in several imbrica- 

 ting series ; the stamens are indefinite in number and 

 inserted at the base of the corolla : the style is promi- 

 nent, with spreading, stigmatic lobes (Fig. 305). The 

 inferior ovary contains numerous seeds, ripening into a 

 smooth or bristly or spiny fleshy fruit, often edible 

 (Figs. 304, 306). 



The largest forms are species of Cereus, with huge, 

 columnar and fluted, spiny bodies, bearing a few clumsy 

 ascending branches, said to sometimes attain a height 

 of 50 or 60 feet. These arborescent forms are especially 

 developed in the drainage basin of the Gulf of Califor- 

 nia. On the western slopes of Mexico proper, and on 

 the eastern slopes of Lower California, these Cactus 

 trees occur in extensive forests, forming the so-called 

 "cardon forests." 



In Bentham and Hooker's Genera Plantarum, 13 gen- 

 era of CactacecB are recognized, while in Engler and 

 Prantl's Pflanzenfamilien, recently published, Schu- 

 mann recognizes 20 genera. Of these 20 genera, 15 are 

 included in trade catalogues, and. five of them are rep- 

 resented in the United States. Generic and specific 

 lines among the Cactacece are very indistinct, and the 

 greatest diversity of opinion in reference to them ex- 

 ists. The group seems to be a very modern one geolog- 

 ically, and unusually plastic, responding readily to 

 varying conditions, so that forms that have been de- 

 scribed as distinct species will undoubtedly prove to be 

 but different phases of a single species. The confusion 

 has been further intensified by the description of nu- 

 merous garden forms. As a result, many catalogue 

 names are very uncertain, being applied differently in 



303, Extreme condensation of the plant body 

 Pelecyphora aseliformis. 



