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NATURALIST'S GUIDE TO THE AMERICAS 



quite homologous with the similar 

 upper Magdalena Valley. The distri- 

 bution of grassland or xerophytic 

 scrub follows the same outline. The 

 prairie is most extensively developed 

 in El Valle over the plain stretching 

 from Tulua on the north to Aganche on 

 the south. Smaller areas of level prai- 

 rie occur near Popayd,n in El Cauca, and 

 in the Patia Valley in Narino. Along 

 the streams palms and bamboos occur. 

 A notable feature of the Cauca Valley 

 are the great marshes, occurring east 

 of the river, a section of which is crossed 

 by the railroad between Cali and Pal- 

 mira. Toward the base of the Central 

 Cordillera, in the subsidiary valley of 

 the Rio La Vieja, is a belt of country 

 apparently originally covered for miles 

 with a solid stand of bamboo. 



Through Antioquia and Caldas, in 

 El Cauca from Aganche to near Popayan, 

 and in portions of the Patia Valley, the 

 inter-Andean Cauca-Patia depression 

 is deeply furrowed by canyons or formed 

 into hills. The slopes and canyon- 

 sides may be open or covered with low 

 brush or with a low xerophytic forest. 

 Epiphytes, while usually rare in such 

 scrub, may occasionally occur in some 

 abundance, with a fair variety of Or- 

 chidaceae and Bromeliaceae. 



Thirteen kinds of birds are known 

 only from the Cauca Valley. The 

 mammal life is that of the upper 

 Magdalena. 



The Cauca Valley has two wet and 

 two dry seasons, the wet seasons being 

 from March to May and from September 

 to November. 



The prairies of the Cauca Valley are 

 intensively grazed and changed by 

 the introduction of drought-resistant 

 grasses, but the rougher surrounding 

 portions have clearly preserved the 

 original flora. The brush-land and low 

 xerophytic forest, except near the chief 

 towns, remain in primitive condition. 



The Llano itself, the true "Valley 

 of the Cauca" may be visited at Cali, 

 Palmira or Buga, all reached by train 

 from Buenaventura. Just east from 

 Zarzal, reached by river steamer from 



Cali, exist xerophytic groves remarkable 

 for epiphytes, and two days by trail 

 eastward, just west of Armenia, one 

 reaches the belt of bamboo. Popayan, 

 accessible by train from Cali to Aganche 

 and thence two days by trail, is in a 

 slightly higher part of the inter-Andean 

 valley. 



6. Pocket-like valleys of grassland and 

 scrub. While pocket-like xerophytic 

 areas are doubtless wide-spread through 

 the Colombian mountains and occur 

 at all elevations, it may be worth while 

 to call attention to two that are most 

 readily accessible. On the railroad 

 from Buenaventura to Cali, above the 

 narrow Dagua gorge and within a sur- 

 prisingly few miles of the wet Choc6 

 forest, one passes into an arid grass and 

 brush-covered valley, its slopes sparsely 

 grassy and its floor with a variety of 

 large Cactaceae. Dagua, the only town 

 between Buenaventura and Cali, is in 

 this arid pocket-valley. On the trail 

 over the Eastern Cordillera from Bogota 

 to Villavicencio one traverses a canyon- 

 like valley with grass-covered slopes 

 and through the midst of its depth roars 

 the Rio Negro, a tributary of the Rio 

 Meta. 



C. Montane forest 



The middle slopes of all mountain- 

 chains in Colombia, whether on the 

 Andean Cordilleras or on the Sierra 

 Nevada de Santa Marta, are clothed 

 in forest. Where the adjacent lowland 

 is forested, as on the western slope of 

 the Western Cordillera and the southern 

 eastern slope of the Eastern Cordillera, 

 the forest is continuous over the moun- 

 tain-bases. From the Santa Marta 

 mountains the forest also descends to 

 some distance upon the plain. On the 

 slopes toward the inter-cordillera val- 

 leys of the Cauca and the Magdalena, 

 forest is only reached at a considerable 

 elevation above the plain. 



The Andean mountain-forests are 

 continuous around the sides, and, 

 when not too lofty, over the summits, 

 of the three Cordilleras. This con- 

 tinuity and the degree of geographic 



