CACTACEiE OP MEXICO SAPFOED. 



557 



Fig. 20. — Carnegiea gigan- 

 tea, fruit nearly ripe. 



The pitahayas of Carnegiea gigantea of Arizona and northern 

 Sonora were noticed as early as 1540 by the members of Coronado's 

 expedition. They are not spiny, like the fruits of Pachycereus, and 

 they burst open when ripe. The pitahaya dulce {Lemaireocereus 

 thurheri) is much sweeter and is covered with 

 stout spines, which grow in clusters from lit- 

 tle tufts of wool. Another columnar cactus 

 with spiny pitahayas is Cereus queretarensis 

 of southern Jalisco, Queretaro, and Guana- 

 juato. The most important edible pitahaya 

 of central and southern Mexico is Lemaireo- 

 cereus griseus (pi. 9, fig. 5), a spherical fruit 

 bearing tufts of sj)ines and w'ool, somewhat 

 resembling the pitahaya dulce of the west 

 coast. Myrtillocactus geometrizans (pi. 9, fig. 

 2) bears the well-known little garambullas 

 offered for sale in the market, either fresh or 

 dried; and in northern and central Mexico 

 several species of Echinocereus, locally known 

 as strawberry cacti, or " alicoches," bear delicious spiny pitayitas 

 (pi. 9, fig. 3) highly esteemed by the natives. 



2. Echinocactus and its allies. — Under the genus Echinocactus 

 Schumann includes several groups of cacti regarded by him as sub- 

 genera. Some of them are treated by other authors as distinct genera, 



although there occur forms which 

 seem intermediate between two or 

 more of the groups. AAHiether or 

 not these groups be regarded as 

 genera, there is no doubt that by 

 separating them from one another 

 and calling them by their distinctive 

 names greater facility wnll be found 

 in recognizing the distinguishing 

 characteristics of the various species 

 and their study will be nuicli sim- 

 plified. 



They may be defined as fleshy 

 plants, globular, oblong, or cylin- 

 drical in shape, with vertical or radiating ribs, or rows of vertical 

 or spiral tubercles, which are usually armed by stout spines. The 

 leaves are reduced to microscopic vestiges or are obsolete. The flowers 

 spring from areoles very near those which subsequently produce the 

 spines. The perianth tube is prolonged beyond the ovary, and is 

 usually covered with scales, either naked or bearing tufts of wool 



Fig. 21. — Echinocactus, flower. 



