A synopsis of the palms of Puerto Rico

by O. F. Cook

The following systematic notes have been accumulated in connection with economic studies of Puerto Rico[^[1]] palms, and although the list is doubtless still incomplete, the printing of it may be justified as a means of securing at least provisional names needed for reference purposes in connection with other publications of a non-systematic character.

The palms may well be considered a very refractory group when handled by the conventional methods of systematic botany. Difficult at once to collect or to study from dried material, they are commonly neglected both in the field and in the herbarium, with the result that literature is scanty and unsatisfactory. A very large proportion of the descriptions are entirely inadequate for the identification of species, and there has been much lawlessness and diversity in the application of generic names, as will appear from some of the instances discussed below. Difficulties of description and classification have also been multiplied by the fact that the palms are such peculiar plants that analogies and criteria borrowed from other families are often inapplicable and misleading. Moreover, the terminology of parts and characters has not been developed to the point where the expression of observed differences is easy, and available language often fails completely to suggest the significance of the characters used. Thus the fibers into which parts of the leaf-bases of many palms are resolved afford many diagnostic characters, for which we have no parallels in other groups of plants.

A compensating advantage may be drawn, however, from the definite and often very limited geographical distribution of the species of palms. Thus, although Puerto Rico is a relatively small island, several of the indigenous palms have apparently ranged in nature over but a small part of it, and a locality definitely indicated would often go further toward establishing the identity of a species than much of the descriptive matter prepared for this purpose. For the present, at least, the geographical idea should be kept uppermost in systematic studies of the palms, since it is generally much easier and far more logical to extend the limits of supposed distribution and unite supposed species, than to cope with the confusion caused by the miscellaneous reporting of species far outside their natural ranges.

From the popular standpoint another serious inconvenience of the systematic literature of palms arises from the fact that it is based so largely on floral characters that even the botanical traveler might need to wait months for the blossoms and then climb the trees or cut them down before being able to secure a clue to botanical names or relationships. But however necessary refinements of formal characters may be in presenting classifications or monographs of large groups, more obvious differences may still be adequate for distinguishing between the species, genera and families represented in a limited flora like that of Puerto Rico. In the present paper use is made therefore of obvious external differences, not only because of the greater convenience and utility of such facts in field study but also in the belief that with the palms, at least, the vegetative, habitat and ecological features are often quite as important for diagnostic purposes as the more technical and conventionalized characters to which botanists are accustomed in dealing with other natural orders.

As will be apparent from some of the following systematic notes, the generic nomenclature of the palms is in a condition closely comparable to that now known to obtain among the myxomycetes, fungi, hepaticae and ferns. Possibly the palms have suffered more from neglect and carelessness than other groups of flowering plants, but it can no longer be maintained that the practical defects of former taxonomic methods do not exist in the phanerogams as well as in the cryptogams, and it becomes obvious that the enactment of different nomenclatorial legislation for these two subdivisions of the vegetable kingdom would be unreasonable and inconsistent.

The present list records twenty palms from Puerto Rico, of which three are introduced and seventeen are supposed to be native species. As may also be inferred from many other groups of plants Puerto Rico appears to be a rather remote corner of the Antillean region, which many types present in Cuba and Jamaica did not reach, whether by reason of greater distance from the continent or because of an earlier interruption of land communication. The native palms of Puerto Rico may thus be said to represent a distinctly Antillean or Caribbean series, only Acrocomia and Bactris being known to have a wider distribution.

The list of introduced palms, consisting of the date, the cocoanut, and the betel, might have been somewhat increased by canvassing ornamental gardens, but it does not appear that any other introduced species has been put to any useful purpose or has escaped into general culture, certainly a remarkable fact when we consider the number and importance of the economic palms of other tropical countries.

Finally, it may be well to note here that several palms have been reported from Puerto Rico which probably do not exist in the island; at least their occurrence is not supported by adequate evidence. Thus Mr. R. T. Hill, of the United States Geological Survey, mentions (Bull. U. S. Dept. Agric., Division of Forestry, 25: 1899) as occurring in Puerto Rico seven palms, as follows: Cocos Mauritia, Oreodoxa oleracea, Cocos nucifera, Martinezia caryotaefolia, Mauritia flexuosa, Oreodoxa regia, and Caryota sp., of which list only Cocos nucifera and Oreodoxa regia appear to have been justified.

The reference to Oreodoxa oleracea is supported by the botanical authority of Professor Drude, but the specimens identified by him as Oreodoxa oleracea (Sintenis collection, no. 1525) and sent from the Berlin Botanical Garden to the National Herbarium and to the New York Botanical Garden are not Oreodoxa oleracea, but belong to the new genus Acrista described below, while a specimen collected by Sintenis (no. 5749) at Aguadilla and sent out from Berlin as an Attalea or related genus is not even a cocoid palm but Areca catechu, the betel nut of the Malay region.

The existence of numerous tubercles on the roots of a young specimen of the royal palm of Puerto Rico is a fact of biological interest and possible economic importance. It was, however, noted so nearly at the end of our last visit that further studies were not practicable, but barring possible nematodes or other pathological causes for the tubercles it appears that we must add palms to the Leguminosae, Podocarpus, Alnus, and Cycas as plants which have, as it were, domesticated nitrogen-collecting soil organisms.