BULLETIN 



OF THE 



TORREY BOTANICAL CLUB 



Vol. XV.] New York. July 2, 1888. [No. 7. 



An Enumeration of the Plants Collected by Dr. H. H. Rusby in South 



America. 1 885-1 886.-I. 



GENERAL FEATURES OF THE REGION TRAVERSED. 



The collections recorded in this series of papers were made 

 during a two years journey along the Pacific coast and across the 

 continent of South America, the special object being the investi- 

 gation of Medical Botany. 



The route of travel covered regions the most diverse as re- 

 gards all the conditions of plant life. North of Guayaquil the 

 coast is verdant, the luxuriant tropical vegetation reaching the 

 very water's edge. But a short distance south of that city be- 

 gins an entirely different region. The eastern cordillera of the 

 i Andes divides South America into two portions, having almost 



nothing in common. While only a few miles in width, this cor- 

 dillera marks differences in soil, climate, and general appearance, 

 as great as any to be observed upon the globe. 



Upon the Pacific side there is a very general dearth of mois- 

 ture, rain being in many places almost unknown, while upon the 

 eastern slope rain is so constant that months may pass when the 

 sun is seen for scarcely an entire hour, and the humidity is so great 

 that clouds of rising vapor sometimes obscure the view of even 

 the nearest objects. The laden clouds that sweep in from the 

 tropical Atlantic lose little of their moisture in crossing the Ama- 

 zonian basin; any loss is but temporary, the equilibrium being at 

 once restored by the soaking up of a fresh supply from the enor- 

 nious water surface that the region presents. But immediately 

 on reaching the mountains, great volumes of water are precipi- 

 tated. The lightened clouds endeavor to escape upward, reach 

 the colder strata, and suffer fresh precipitations. This process is 

 continued over a belt of two hundred and fifty miles of steadily 

 increasing elevation, until the winds which cross the cordillera 



V. 



'I 



