everjrrpcn if in full leaf throujrh the year or de- 

 ciduous if leafless or nearly so for a brief period, 

 such as in the dry season of late winter. Hut- 

 tresses, or eidarged narrow outgrowths at the base 

 of the t runic of large trees continuous with lateral 

 roots, are noted if jM-esent. Data on shape of 

 crown, branching, and twigs are added for many 

 species. Notes on bark include color of the sur- 

 face and texture, whether smooth or rough, and if 

 fissured (with many nai'row thin cracks) or fur- 

 rowed (with broad deep grooves). As most trees 

 have thin bark less than 1/2 inch in thickness, men- 

 tion is made of thick barks. Color and taste (also 

 odor if present) are given for the inner bark, that 

 is, the living tissues expcsed by cutting beneath the 

 surface, since these details often are helpful in 

 field identihcation. 



Leaves, Flowers, and Fruits 



Because of their importance for identification, 

 the leaves, flowers, and fruit are described in de- 

 fail and with measurements for reference. How- 

 ever, characters enqihasized in the first paragraph 

 are not repeated below. Descrijifive terms are de- 

 lined under the topic "P^xplanation of Botanical 

 Terms"' (p. 9). 



Months or seasons of flowering and fruiting, as 

 far as ktiown, have been compiled from various 

 sources. For a few years personnel of the United 

 States Forest Service made field observations of 

 time of flowering and fruiting of many Puerto 

 Ricau tree species, which were summarized in a 

 card file. Herbarium specimens collected by per- 

 sonnel of the Forest Service at different times of 

 the year have contributed additional dates, as have 

 tlie floras by Urban (37) and Stahl {35). Some 

 tree species are cited as flowering and fruiting 

 probably or nearly through the year. This state- 

 ment means not that a particular tree bears flowers 

 and fruits almost continually, but that on almost 

 any date some trees may be found in bearing con- 

 dition. An individual may have more than one 

 blossoming period during the year. Generally 

 flowering of trees is greatest from March to May, 

 after the start of the spring rains. 



Wood and Uses 



The wood is described briefly, including notes 

 on color of sapwood and heart wood, hardness, 

 weight and specific gravity, and durability. These 

 notes are chiefly from Puerto Rican specimens sup- 

 plemented for some species by published descrip- 

 tions from other rtreas. Detailed data on wood 

 properties and uses have been condensed from the 

 recent publications by Longwood {2i2, 23). The 

 specific gravity values quoted to two decimal places 

 were based on green volumes and are slightly lower 

 than other values based on air-dry volumes. Rel- 

 ative resistance of the wood to attack by ch-y-wood 

 termites has been compiled from Wolcott (4^)- 

 Uses of the wood are primarily those of Puerto 

 Rico, but special and different uses elsewhere are 



mentioned. IVfost of the native woods are avail- 

 able only in limited ([uantities, and none is suffi- 

 ciently al)undant for export. Nevertheless, as 

 Longwood i-eported, many of these woods could 

 be utilized in additional ways. 



Other Uses 



Other purposes served by Puerto Rican trees 

 are noted. Many kinds are planted for fruit, 

 shade, and ornament. Others have bark that 

 yields tannin, fibers, or dyes or have parts em- 

 ployed in home medicines. Shade and ornamental 

 frees of Puerto Rico have been li.sted by Winters 

 and Almeyda {39) and by Martorell ("^4). The 

 last has prepared also a list of trees that should not 

 be planted because of insect pests or diseases, and 

 these objections are incorporated here. Special 

 mention has been made of the tree species intro- 

 duced and hardy in subtropical parts of the United 

 States, mainly southern Florida and southern Cal- 

 ifornia, where they are cultivated for fruit, shade, 

 and ornament. Sturrock and Menninger {36), 

 Menninger (,^6', '27), Morton and Ledin {28), ancl 

 Barrett {2) have published further information 

 about these. Many trees are classed as honey 

 plants by Ordetx {31) and others, because their 

 flowers attract bees and secrete nectar in quantities. 



Propagation, Gro'wth, and Other Notes 



Brief notes on propagation, growth rate, and 

 site adaptability of many forest and planted trees 

 have been summarized from records of the United 

 States Forest Service, and other miscellaneous 

 notes of interest have been added. Further details 

 and methods on propagation of trees in Puerto 

 Rico are contained in the manual on that subject 

 by Gilormini {11). Additional information on 

 forest management of many Puerto Rican tree spe- 

 cies may be found in various articles in The Carib- 

 bean Forester. 



Distribution 



For each tree species the natural distribution or 

 range is stated, both in Puerto Rico and the United 

 States and British Virgin Islands and also beyond 

 through the West Indies and continental tropical 

 America. Introduced trees, often spreading from 

 cultivation and becoming naturalized, are further 

 designated by mention of their native home. 



Names of individual islands belonging to Puerto 

 Rico and the Virgin Islands where each species is 

 known are recorded, mainly from the published 

 ranges by Brifton and Wilson (-5) supplemented 

 by the authors' field records. The first map (fig. 

 1) shows names and locations of the principal 

 islands. Largest of those under Puerto Rico are 

 Mona on the west and Culebra and Vieques on the 

 east. Other small islands of botanical intere.st 

 noted by Britton and Wilson are Desecheo at the 

 west, Caja de ]\Iuertos on the south, and Icacos 

 near the di-y northeastern corner. 



