Jennings: Contribution to Botany of Isle of Pines. 29 



the Isle of Pines, of Rhizophora Mangle but, towards the land, this 

 species is mainly supplanted by the White Mangrove, Avicennia 

 nitida. Under these latter trees are large tussocks of Acrostichum 

 aureum, the leaves of this fern often reaching a height of five or six 

 feet. In the clumps of Acrostichum, but apparently rarely forming 

 tussocks independently, are great clumps of Nephrolepis biserrata. 

 The ground under the Avicennia is often covered almost completely 

 by Batis maritima, this species constituting there a distinct society. 



2. The River-hank Forest Formation. 



This forest constitutes a veritable jungle along the banks of the 

 rivers where the water is non-saline. Among the various trees of 

 this forest some of the most prominent are the royal palm (Roystonea 

 regia), the majagua {Hibiscus tiliaceus), and the alligator-apple 

 {Annona palustris). There are a large number of smaller trees, 

 shrubs, and herbaceous plants competing vigorously for space, among 

 these being Lonchocarpus latifolius, Hirtella mollicoma, Eugenia fara- 

 moides, Ternstrozmia obovalis, Dendropanax cuneifolium, Xylopia 

 grandiflora, Matayha oppositifolia, Cyrilla racemiflora, Cecropia peltata, 

 Miconia tomentosa, and Miconia prasina. 



This forest extends in an ever narrowing fringe up the rivers and 

 terminates in a scattering fringe, or in a series of individuals, along 

 the banks of periodically dry arroyos. This constitutes a more or 

 less distinct vegetational unit, which may be termed the "Arroyo 

 Formation." 



3. The Arroyo Formation. 



This vegetation is characterized best, perhaps, by Chrysobalanus 

 pellocarpus, the Coco-plum. Accompanying this species are various 

 other shrubs and smaller plants, many of them common in the river- 

 bank forest. This is the habitat of the tree-fern, Alsophila 

 myosuroides and of Adiantum fragile and Adiantum cristatum. 



4. The Freshwater Lagoon Formation. 



While there are apparently some good examples of this formation 

 in the southern portion of the island, little opportunity was afforded 

 to study them. At Los Indios the river forms an ox-bow approaching 

 lagoon conditions. Here were Castalia ampla and Utricularia spir- 



andra, and the small pond about one and one-half miles east of Nueva 



Gerona also shows this formation. 



