Jennings: Contribution to Botany of Isle of Pines. 31 



where too sandy. It is preeminently characteristic of the " Mai Pais " 

 gravels near Nueva Gerona, and is itself characterized by a con- 

 siderable number of species of scraggly shrubs and palmettoes, asso- 

 ciated rather openly on a more or less grassy plain. The most char- 

 acteristic of these shrubs are Byrsonima crassifolia, Miconia delicatula, 

 Tabebuia lepidophylla, Brya Ebenus, Curatella americana, the large- 

 leaved and mullein-like Byrsonima verbascifolia, and the common 

 palmetto, perhaps the most characteristic species of the savanna, 

 Acozlorraphe Wrightii. 



Probably these savannas largely owe their existence, at least their 

 very open character, to the grass and brush fires which formerly were 

 of common occurrence during the dry season. If left undisturbed, 

 there can be little doubt that much of the savanna would eventuolly 

 pass more or less completely into the Open Forest Formation. 



11. The Open Forest Formation. 



This consists of an open pine forest with palmettoes and a sparse 

 undergrowth of many of the species characteristic of the savanna. 

 The pine is Pinus caribcea and the formation occupies the higher and 

 drier parts of the " Mai Pais" gravel plain, towards Los Indios merg- 

 ing into the pine-barren forest. The open forest formation, as noted 

 above, would very likely succeed much of the savanna were it not 

 for man's use of the trees and for the fires. 



12. The Pine-barren Formation. 



I have seen fit to distinguish between this open pine forest, of the 

 white sands and gravels of the Los Indios region, and the "Open 

 Forest Formation." In the pine barrens the soil shows its acid char- 

 acter and the undergrowth is not to any large extent composed of 

 species characteristic of the savanna. 



These lower plants constituting the undergrowth are Pachyanthus 

 cubensis, Pachyanthus ovatus, Kalmiella aggregata, Miconia delicatula, 

 Polygala uncinata, Xolisma myrtilloides, Pinguicula filifolia, Stenor- 

 rhynchos squamulosus, Tetramicra Eulophice, etc., altogether a con- 

 siderable number of interesting plants not found elsewhere on the 

 island but some of them occurring also in Pinar del Rio Province, 

 Cuba. 



13. The Tropical Forest Formation. 



This is the hardwood forest formation covering the crystalline 

 limestone hills and ridges and the limestone plain constituting the 



