t68 PRINCIPES [Vor 28 Principes,28(4), I984, pp. 168-172 The Native Palms of Puerto Rico ANonew HnNoBnsoN The New York Botanical Garden, Bronx, Neu York, NY 10458, U.S.A. Puerto Rico is one of the Antilles, an of this:is unknown, and it seems unlikely island chain curving from Florida to Ven- that it is entirely due to climatic changes. ezuela, dividing the Atlantic Ocean from The pattern of forest destruction in the Caribbean Sea. It is the easternmost Puerto Rico is the same as that found in of the four Greater Antilles, the others many areas throughout the Caribbean. being Cuba, Jamaica and Hispaniola. It is During the last 100 years there has been also the smallest, about 100 miles long extensive deforestation, leaving today only and 40 miles wide. The flora is distinctly a small fraction of climax vegetation. For- Caribbean,and while the palms are not so tunately a well-developed conservation diverse as those of Cuba, they are no less program has ensuredthat someof the most interesting. Puerto Rico has ten native interesting vegetationtypes are preserved speciesin ten genera, and half of these in national parks. These include subtrop- are endemic(Little and Wadsworth 1964; ical dry forests, e.g,, at Guanica, subtrop- Little, Woodbury, and Wadsworth I974). ical wet forest, e.g., at Maricao, and both The most widespread and abundant species is Roystonea borinquena,, the 'opalma real." This palm is endemic to Puerto Rico and three smpll neighboring islands. It is a large and imposing palm, easily recognizedat a distanceby its stout grey trunk and large head of pinnate leaves. It is seen throughout the island in lowland forests, fields and planted as orna- mentals. The fruits are used by farmers to feed hogs. It is said that you can tell the number of hogs a farmer owns by the number of roystoieas he has dn his iand, usually four palms to a hog. Although farmers are thus inclined to conservethese palms, it seems that roystoneas actually benefit from forest clearance, and can extend their range in cleared areas.There are about eleven other speciesof Roys- tonea. wirh a circum-Caribbean distribu- tion. However, their variability, and fre- quency with which they are planted, means that their taxonomy is in a state of some confusion. Roystonea borinquena has a distinctive bulge in the tn:nk, and so do I. Roystonea borinquena, the most frequent palm someof the other species.The explanation in Puerto Rico. L9841 HENDERSON:PALMS OF PUERTORICO 169 lower montane wet forest and lower mon- tane rain forest, e.g., at Luquillo. Also sec- ondary forests have increased in area in recent years as a result of the abandoning of marginal agricultural areas. In the limestone hills of the island, Thrinax morrisii is commonas an under- story shrub. Typically it occurs in large populationsof sterile sternlessplants with a few fertile specimenswith stems up to 2 m. The habitat of this speciesis similar to that of other related Caribbean palms, e.g., Coccothrinax, and.consists of xeric limestone areas with a seasonalsubtropi cal climate. The common name of T. mor- rlsii is "palma de escoba,"and this refers to the practice of making broomsfrom the leaves.This was a common industry many years ago, which then declined. Now, because of the economic recession, the practice has started up again, and brooms can be bought in local shops. 2. Thrinax morrisii, growing in limestone rocks. 3. Sabal causiarum, the Puerto Rican hat plant. PRINCIPES [Vor. 28 4. Gaussia attenuala, the spineJike projections on 5. Calyptronoma riaalk, the rarest palm in Puerto the roots, anchored in limestone rocks. Rico, growing beside a stream near San Sebastian. Thrinax morrisii is very similar to There are two spiny pinnate-leaved another palmateJeavedpalm, Coccothri- palms in Puerto Rico, Acrocornia media nax aha. but the latter is more common and,Aiphanes acanthophylla. The latter in wetter limestone hills in the north of is rare in the forests of the subtropical 'haystack the island. The two genera can easily be moist zone, on the hills' in the separatedbecause the basesof the petiole north of the island. It is easily distin- n Thrinax are split, while they are not in guished, not only by its spines, but also Coccothrinax. by the truncated, jagged ends of the leaf- The only other palmate-leavedpalm in lets. The only other sptny palm, Acro- oopalma Puerto Rico is Sabal causiaranz.This is cornia ntedia, the de corozo,'ois another endemic species,and is found on common at lower elevationsin forests and coastalplains in the north and west of the fields. This specieshas deciduous spines island. Its stout grey trunks, up to l0 m, on its trunk, and is found only in Puerto are a distinctive feature. It is known as Rico and one of the Virgin Islands, St. "palma the de sombrero," although the Thomas. practice of making hats from the leaves In the hills between San GermSn and has declined over the years, with cheaper Lajas, Gaussia attetuua,ta,is frequently ones being made in other islands. Sabal seen. It grows on ridges and sticks out is another Caribbeangenus, but with wider above the surrounding vegetation, the inland extensions. Typically it inhabits slender leaning trunk supporting a small lowland coastal regions, often on sandy head of pinnate leaves.Normally only iso- soil. Again there is great diversity in this lated specimensare seen, and in contrast genus,Ieading to much confusionin nam- to palms \ke Roystonea, it disappears ing. when its habitat is disturbed. This palm is I 9841 HENDERSON:PALMS OF PUERTORICO species,invading areas that have been dis- turbed naturally, either by landslides or hurricanes. Others think that P. montana .domi- is a typical climax species, and its nance in steep r,vet areas is a result of its ability to anchor itself by means of numer- ous above-ground roots. Set against both these theories is the fact that this palm is very slow growing, only 20-30 cm per year, and despite its tremendous repro- I ductive ability (5,000 seeds a year per mature tree) only one in a million seeds I reaches maturity (Bannister 1970). There are also some interesting associations between this species and other animals and plants. The seeds are eaten by scolytid beetles (Janzen I972) and the flowers are bee-pollinated. The trunks and leaves of the palms are often covered with epi- phytes, from lichens, mosses and liver- worts, to ferns and flowering plants, such as bromeliads and orchids. the rarest Puerto Rican palm ' ,. Acrocomia media is common in lower eleva- Certainly tions in forests and fields. is the endemic Calyptronorna riualis. It was discovered in l90l by O. F. Cook, endemic to Puerto Rico, and although not beside a small stream between Lares and common it has two strongholds, not only San Sebastian. It is still there today, and irr the San German hills but also in the has recently been {ound in a second local- northeast of the island near Manati. The ity nearby. The original site contains about roots of this species are interesting. They 30 mature specimens, and since they are are visible above ground and are covered all on private land they are in a perilous rvith spirally arranged spine-like projec- position. Part of one colony has recently tions. There is only one other species, been destroyed, but it is to be hoped that Gaussia princeps from Cuba. Like Thri- the high level of interest by local botanists nax and Coccothrinax, Gaussia only will ensure their survival. There are other grows on calcareous soils, although it is in closely related species of Calyptronoma I no way related to these two coryphoid in the Caribbean, and three closely related genera, being a member of the chamae- genera, Calyptrogyne in Central America I doreoid group of palms. and, Pholidostachys and. Weffia in both In the wet forests of the Sierra de Central America and northern South Luquillo and the Cordillera Central Pres- America. They are all allied to the large toea mnntana (syn. Euterpe gLobosa) is genus Geonoma. abundant, at altitudes of 300 to 1,000 m. The tenth and last Puerto Rican palm There have been numerous ecological has least claim to be included in the flora. studies in these forests and much is known One single specimen of Pseudophoenix "palma about the ecology of this palm, the sarsentii has been recorded from Mona de sierra." It often occurs in dense strands, Island, 35 miles west of the main island. known as palm brakes, in very wet soil of This represents the eastern limit of this steep slopes. Some ecologists believe that species which is found from Hispaniola to this palm is a secondary successional Mexico. 14, PRINCIPES [Vor. 28 Acknowledgments rainforest. U.S. Atomic Energy Comm., Wash- ington, D.C. My thanks to the many botanists in JANZEN,D. H. 1972. Association of a rainforest Puerto Rico who were so helpful to me on palm and seed-eatingbeetles in Puerto Rico. a recent visit to the island. Ecology 53: 258-261. Lrr,rr, E. L. eNo Weosvonrs, R. H. 1964. Common Trees of Puerto Rico and the Virgin Islands. Agriculture Handbook No. 249. USDA LtrpR.ttune CIrrl Forest Service. Lrrrru, E. L., Wooosunv, R. O. eNo Wenswonrs, BANNISTER,B. A. 1970. Ecological life cycle of F. H. 1974. Trees of Puerto Rico and the Euterpeglobosa Gaertn., p. B-299-3I4. InH. Virgin Islands. 2nd Vol. Agricultual Handbook T. Odum and R. F. Pigeon (Eds.). A tropical No. 449. USDA Forest Service. LETTERS Dear Editors and Contributing Writers, Philippines also.