CACTUSES IN- DOORS AND OUT. 



are flat jointed, four 

 seventeen of these 



; the whole valley of 



TIA RaFINESQUII. 



and the country of 

 ary. This has thus 

 namely, five mamil- 

 ;ies ; six echinocacti, 

 ven cerei, represent- 



wanting, and beyond the Missouri, at Rainy Lake (49°), 

 there onl)' remains one species, Opttnlia Missoiirieiisis. 

 This species here marks the extreme limit of this type 

 of vegetation. In the region of the Missouri this spe- 

 cies is very common, being one of the 

 characteristic features of these prairies, 

 and the more so as no cactus forms are 

 found in the North American woods. 



"The succulent forms which unite the 

 Mexican flora with that of the southern 

 prairies often forms, upon the highlands 

 of Mexico, the most abundant and char- 

 acteristic product of the dry and rocky 

 soils. Nearly all the cacti found in our 

 greenhouses come from Mexico. There 

 they are found in nearly all parts of the 

 country ; a few mamillarias grow at an 

 elevation of 11 000 feet. Only the phyl- 

 locactus, which is never found upon the 

 prairies, and whose stem has the flattened 

 form of a leaf, is limited to the shady 

 woods of the hot regions, 



" Upon the cliffs of the West Indies the cereus is 

 found in great profusion, being over twenty feet high. 

 It was once thought that these had been carried from 

 the continent, but a more careful examination proved 



462 



two opuntias ; of these last twelve 

 clavate, and five cylindrical ones ; 

 species are peculiar. 



"6. 7 lie Gila Region, comprising 



Fig. I. Opun 



the Colorado south of latitude 36° 

 the Gila, its large southern tribut 

 far furnished thirty-six cactaceae, 

 larias, three of them peculiar spe^ 

 none of them found elsewhere ; se 

 atives of each of our four sub-genera, and five of them 

 peculiar ; eighteen opuntias, of which six (all peculiar) 

 belong to the flat kinds, two to the clavate and ten to the 

 cylindric division; one of the former and nine of the 

 latter are peculiar. 



"7. The Calif oniia Region, namely, California west of 

 the Sierra Nevada, and comprising the southwestern 

 part of the present state of California, produces six 

 cactaceae, five of which are peculiar. They are one 

 mamillaria, one echinocactus, one cereus and three 

 opuntias. 



"8. The NortJiwestern T?!'^'/!';/, comprising the north- 

 ern parts of the state of California, the territories of 

 Utah, Oregon and Washington. This region has so far 

 furnished only a single opuntia (from eastern Oregon), 

 common also to the Missouri region." 



Later researches have increased the number of species, 

 but their relative distribution remains about the same. 



The more general distribution of cactuses is well told 

 by Grisebach in his Vegetation der Erde : "The dry cli- 

 mates of America are most sharply distinguished from 

 similar places in other parts of the world by their cacti. 

 These comprise a large and distinct family, native only 

 to America. Cactuses reach their greatest perfection in 

 the tropical zone, upon the rocky plains of Mexico and 

 upon the Andes of South America. In the Colorado re- 

 gion, they shrink during the winter from loss of sap and 

 assume a red color, as if a continual period of growth 

 were a necessity which they cannot easily satisfy. The 

 southern prairies have as great a variety of peculiar 

 forms as the tropics, and all the principal forms of the 

 family are found there. But northward the number of 

 species rapidly diminish, the large and massy ones are 



