368 ANNUAL. REPORT SMITHSONIAN INSTITUTION, 1924 



unlikely that at any other time of year it would be possible to find 

 a greater projDortion of the plants in blossom. At any season some 

 orchids are in bloom, but each species probably has a more or less 

 well defined flowering period, and in order to obtain the complete 

 orchid flora of a locality it would be necessary to visit it every month 

 in the year. Some remain in flower only a few days, while with 

 others the blooming period is greatly prolonged. 



PACIFIC SLOPE 



So little time was spent upon the Pacific coast, near Orotina, that 

 it is impossible to make any generalizations of value. It may be 

 stated definitely, hoAvever, that the whole flora here is far less varied 

 than elsewhere in Costa Rica, and that in a day's collecting one can 

 find only a fraction of the number of plants to be obtained in other 

 parts of Costa Rica in the same length of time. Moreover, the 

 plants are less interesting and consist chiefly of species having a 

 wide distribution in tropical America. Most of the land is now un- 

 f.orested. Where forests do occur they are moderately dense and 

 consist of a limited number of species, many of which lose their 

 leaves in the dry season. In the heavier forest the undergrowth is 

 little varied and lacks many of the conspicuous plants of the Atlantic 

 coast. Ferns are very few, and the species mostly uninteresting. 

 These conditions must be understood as prevailing only at lower 

 altitudes, on the hills and in the plains near the coast. Upon the 

 mountains of the Pacific coastal region conditions are more favor- 

 able. 



About Orotina orchids were rather plentiful as to individuals, 

 but appeared to represent only a few species. Not many were in 

 flower during the dry season. Most conspicuous was Epidendrum 

 atropurpureum (pi. 7, fig. 1). In the forests the orchids are confined 

 mostly to the upper branches of the trees, where it is difficult or 

 impossible to collect them. On some of the small trees scattered 

 about the fields and pastures the case is different. It is a well 

 attested fact that certain species of trees are preferred by orchids, 

 and that there are others upon which they never grow. The favorite 

 tree of all is probably the calabash (Crescentia cujete), which is 

 seldom without its quota of orchid epiphytes and often is almost 

 completely covered with them. The mango, strangely enough, is 

 another favorite tree for certain species. About the Canal Zone, 

 where mangoes have run wild through the forests, there is almost 

 always a goodly number of orchid plants upon them. Wild figs, 

 on the other hand, are usually almost or quite free of epiphytes. In 

 general, it seems that smooth-barked trees are little frequented by 

 orchids, although the smoothness of the bark scarcely seems an ade- 



