A synopsis of the palms of Puerto Rico

by O. F. Cook

Family ARECACEAE

A large family, with abundant genera in the tropics of America and Asia, but absent from tropical Africa. The Puerto Rico representatives may be recognized very easily by the fact that the leaf crown is supported upon a column of the sheathing bases, a character of which the royal palm furnishes a conspicuous and ever-present example. Of the remaining genera, one, the betel palm of the East Indies is sparingly introduced about towns in the western part of the island and may be recognized at a glance by reason of the extremely dark green of its foliage. The other two genera are native palms confined to uncultivated areas and thus seldom seen at close range from traveled roads. The mountain palm, Acrista, covers the summits of many of the mountains of the island, but Aeria seems to be confined to the range of high limestone crags which skirt the northern coast of the island between Bayamon and Arecibo.

Key to the Genera of Arecaceae

Trunk tall and slender, tapering from a swollen base; spathes numerous (7); inflorescence appearing in the axis of the rather persistent lower leaves, long and slender; staminate flowers arranged in rows.

Aeria.

Trunk robust or of uniform diameter; spathes 1 or 2; inflorescence short and brush-like, not exposed until the enclosing leaf below it falls away; flowers not set in rows.

Spathe single, the fruits 2.5 cm. long; leaf-divisions upright, very dark green.

Areca.

Spathes 2, fruits less than 1.25 cm. long; leaf-divisions horizontal or oblique.

Trunk robust, thickened near the middle; leaf-divisions inserted by twos and standing at different angles; inflorescence twice or thrice branched, standing close to the leaf-bases.

Roystonea.

Trunk slender, of uniform diameter; leaf-divisions at equal distances, horizontal; inflorescence once-branched, at maturity 15 cm. or more below the leaf-bases.

Acrista.

Aeria gen. nov.

A tall slender palm evidently related to Gaussia, but the embryo lateral instead of basal, and the pinnae without basal cushions.

Among palms in Puerto Rico Aeria resembles only Acrista, from which it is readily distinguishable by the very slender habit, the swollen base of the trunk, the much-branched slender interfoliar inflorescence, the shorter sheathing bases of the leaves, and the numerous spathes.

The embryo of Aeria is located near the longitudinal middle of the seed on the side opposite the rudiment of the style, which is here located at the base of the fruit instead of on the side as in Acrista. The albumen is also uniform, except for a small central cavity and the outer covering is fleshy rather than fibrous.

The position of the embryo is, perhaps, the most obvious difference between this genus and Gaussia, but there are several other significant discrepancies. Thus the flowers are arranged 3 or 4 in a row, very seldom 5 or 6. Three fruits develop from one flower only exceptionally. The trunk is of more than medium height, and the inflorescence is in reality infrafoliar, for although the dead leaf-bases and midribs of the leaves are persistent and support the long inflorescence, this condition is not comparable to that of the cocoid and other really interfoliar inflorescences.

Aeria attenuata sp. nov. [Plate 45.]

The tallest of Puerto Rico palms, probably attaining 30 metres and upward. The trunk is supported on a mass of coarse roots with spine-like projecting rootlets arranged in whorls. The surface of the trunk is smooth with very faint annular impressions. Near the ground the diameter is 12 to 15 cm. and increases upward to about 25 cm. at about 3 m. above the base. Above this swelling the trunk tapers very gradually and in tall specimens is less than 7 cm. in diameter at the top.

The sheathing leaf-base is only 20 cm. long. The leaves remain attached long after the rupture of the open side, but no fibers are formed, the edges of the split side being fringed only with brown membranous shreds. The petiole is rather short, round and rigid and the rachis is prominently angled above.

Segments of a rather firm texture and standing in different planes, but all more or less upright or oblique to the rachis, segments from middle of leaf 2.3 cm. wide near the base, 3.8 cm. long. The segments are set very closely together, especially the proximal, and overlap each other in a succubous manner. Fresh fruits deep orange in color and of an unsymmetrical oval in shape, 16 mm. by 12 mm., with a firm, fleshy outer covering 1.6 mm. thick, adherent to the seed, the three persistent styles remain of the same size and are located at the base of the fruit.

The seed is flattened oval, 11 mm. by 9 mm., with a prominent basal tubercle (hilum). The surface is brownish with a few shallow impressed lines, but the albumen is white and uniform. Flowers and ripe fruit were obtained at Vega Baja in December, 1899; type specimen no. 1040.

The so-called llume palm is a most striking ornament of the rugged limestone hills from Vega Baja to Manati and Arecibo. At a sufficient distance the slender trunk is no longer visible and the crown of leaves appears as if suspended in mid-air, while at closer range it does not seem possible that so slender a shaft can maintain itself. This very slenderness with the attending flexibility is however, an element of strength since it permits the trees to bend before the wind while the leaves diminish the resistance by straightening out as in the cocoanut. The hurricane of August, 1899, seemed to have done little damage to these tallest of Puerto Rico palms, many of which project for more than half their height above everything standing about them. As the trees of the rather sparse forest growth of these hills are commonly from 12 to 18 metres tall, the llume palms must often attain upwards of 30 metres.

Areca Catechu Linn. Sp. Pl. 1189. 1753

In the western end of the island the betel palm of the Malay region has been sparingly introduced, though the fact does not seem to have been reported hitherto. A few were seen in gardens about Mayaguez and others in and near San Sebastian. So far as we were able to learn, the people do not know the name or nature of this introduced species which is apparently planted only as an ornament or a curiosity. The form is not unpleasing, but the extremely deep, sombre green of the foliage seems almost unnatural and imparts a suggestion of artificiality.

Only photographs and fruits of Areca were secured at San Sebastian, but Puerto Rico specimens collected by Sintenis (no 5749) at Aguadilla have already been distributed from the Berlin Botanical Garden with the label “Palma Spec. Subtrib. Attaleae.”

ROYSTONEA Cook, Science, II. 12: 479. 1900

Oreodoxa Martius and more recent authors, not Willdenow.

The history of the generic name Oreodoxa shows that botanical writers of the last few decades have been in error in removing the two original species and applying it to another series of similar but not closely related forms. To avoid further confusion with reference to a name which by reason of the conspicuous character of the trees has wide use in popular literature it seems desirable to add the following notes on the genus Oreodoxa as originally established by Willdenow in the Memoires de l’Academie Royale, Berlin, 1804, a publication which seems to have been consulted very seldom, even by writers on palms.

Spathe universal, univalvate; spadix ramose, perianth monophyllous, tripartite below, the divisions ovate, acute, concave; petals ovate, acuminate, concave. Filaments six, of the length of the corolla; anthers oblong, acute. Style tripartite, shorter than the filaments, stigma acute. Ovule, drupe, and seed globose; drupe succulent, but slightly fibrous; seed single, cartilaginous, nearly smooth, marked with a longitudinal sulcus. In the discussion subsequent to the statement of the above characters, Oreodoxa is said to be distinct from Bactris in the tripartite style and in the absence of the “ordinary three impressions”; it is distinguished from Areca, then supposed to include Euterpe and species now generally placed in Oreodoxa, in the single spathe, the triple style and the hermaphrodite flowers.

The first species is Oreodoxa acuminata, referred by recent authors to Euterpe but probably constituting a distinct genus. The trunk is erect, cylindrical, very smooth, and attains a height of from 15 to 18 metres; the “root” throws out suckers at the base of the trunk. The fronds are pinnate, with opposite or alternate, very long, ensiform, acuminate pinnae, replicate at base. The strongly convolute young leaves form a green apex for the trunk, five feet high. Spathes cinereous, folded in at the base of the leaf-sheaths at the top of the trunk, univalvate, deciduous; spadix erect, much branched, having the appearance of a broom.

The heart of the bundle of leaf-bases, about two feet long and three inches thick is eaten as a salad, with oil and vinegar. It is also stated that the deciduous boat-shaped spathes serve as reservoirs of rain-water which is long retained in the cool shade cast by the trees. Birds and beasts, and human natives as well, are said to be dependent at times upon the liquid thus stored, since in the regions where the palm grows there are at times no other means of procuring water. The forests of the high mountain chain of Buena Vista in the province of Caracas are the native home of the species. It thus appears that in addition to the structural differences Oreodoxa acuminata occupies quite a different place in nature from that of the more thoroughly tropical species commonly referred to that genus, and the stoloniferous habit also indicates a different ecology.

The second of the original species of Oreodoxa is now referred to the genus Catoblastus. It is a somewhat smaller tree from 12 to 15 metres high, with a generally similar habit, and is also stoloniferous, but the pinnae are broad, cuneiform and praemorse, or irregularly truncate as in the species generally referred to Martinezia. The drupaceous fruit is grayish and the pulp is only slightly succulent; seed the size of a pigeon’s egg, its exterior brown, marbled with numerous veins. In the characters of the spathe the arrangement of the fruit and the edible quality of the heart of the leaf-cluster, as well as in the formation of lateral off-shoot this species is said to be similar to the first.

Botanists are not yet agreed upon the methods of dealing with complications like the present in regard to the names of plants, but it appears certain that those who do not recognize Oreodoxa as a genus distinct from those admitted in the more recent works on palms must associate it either with Euterpe or Catoblastus. The latter name it would in that case replace, being much older. Moreover, unless we are prepared to disregard Willdenow’s statements concerning the stoloniferous trunk, the simple spathe and the hermaphrodite flowers, to say nothing of many minor points of circumstantial evidence, there is no scientific warrant for applying the name Oreodoxa to the noble Antillean species with which it has been universally associated.

The dried specimens which Willdenow studied were supplemented by notes of field observation by a court gardener, who was evidently also a botanist of some experience, to whom Willdenow refers as his “friend.” The living colors are described with considerable detail throughout the entire paper, which renders noteworthy the fact that the spathes are stated to be cinereous. This is in agreement with species of Euterpe which have membranous spathes, but indicates a wide difference from the West Indian trees where the spathes are thick and fleshy and remain vivid green until they open and fall away.

The name Roystonea has been given to this ornament of the Puerto Rico landscape as a respectful compliment to General Roy Stone, the American engineer officer who secured the admiration of the people of Puerto Rico by his fearlessness and conspicuous energy in the Adjuntas road-building campaign which flanked the line of Spanish defenses, and whose subsequent interest in the improvement of the island will undoubtedly affect its future history.

Roystonea Borinquena sp. nov. Plate 45. f. 2.

Trunk normally fusiform, 30–60 cm. thick, 12–18 m. high. Leaf segments 4–4.4 cm. in width. Inflorescence robust, compact, twice branched, the branches numerous and coarse, ferruginous, pubescent. Fruits long-oval, yellowish brown at maturity. Seeds 8 mm. by 6.3 mm., flattened about the hilum, rounded below; wall of endocarp smooth, adherent over a small area.

The royal palm of Puerto Rico differs from that of Cuba in having the trunk generally shorter, more robust and more distinctly fusiform. The inflorescence is twice branched, with the branches more densely clustered, coarser and darker colored than those of the Cuban royal palm, Roystonea regia. They are also covered with a slightly hispid brown pubescence while Cuban specimens are much smoother and more pallid. The difference of habit, to judge from photographs of the Cuban species, is most apparent when the trees have grown in the open, as when planted in avenues or along roadsides. In Puerto Rico, trees which are obliged to compete with other vegetation are often tall, slender and unsymmetrical. The typical form is shown in our photograph (no. 250) taken in the plaza of Juana Diaz.

Martius gives the width of the pinnae of the Cuban royal palm as from 8 to 12 lines. Cuban specimens show as much as one inch and a quarter, while others from Porto Rico are half an inch wider (44 mm.) of somewhat coarser texture and with more widely separated secondary veins. The fruits of the Puerto Rico palm are a deep yellowish brown when ripe, while those of the Cuban are said to become violet or bluish black. According to Martius, the fruits of the Cuban species are 6 lines by 4, but dried specimens show no such discrepancy of proportions and measure only about 8.5 mm. by 7.5 mm.

In Puerto Rico the fresh fruits are also much longer than broad, perhaps even more slender than the figures given for the Cuban; when dry they still appear somewhat longer and larger than the latter.

The seeds of Roystonea Borinquena differ in several particulars from those of the Cuban species. In shape they are longer and less spherical, measuring 8 by 6.3 by 5.5 mm. instead of 7.8 by 7 by 6 mm.; the side bearing the hilum is much flattened and even slightly concave; the fibers radiating from the hilum are longer, and the corner between the hilum and the micropyle is evenly rounded, not sharply squared and prominent as in R. regia. On the back of the seed the smooth inner wall of the endocarp is closely adherent over a small area, while in Cuban seeds this wall remains attached over nearly the whole side and is furthermore distinctly rugose-coriaceous on the surface, and has a distinct sulcus in the median line.

The royal palm is not only the more conspicuous and characteristic natural object in most parts of Puerto Rico, but it probably exceeds the cocoanut in total economic importance. The most useful part is the yagua or sheathing base of the leaf, with which a large proportion of the houses of the poorer classes are thatched or sided, or both.

The royal palm is one of the wild species which has been distinctly advantaged by human interference in natural conditions. It is a general fact that outside the climbing species palms are not successful in competing with tropical forest vegetation. Originally the royal palm and the corozo were probably confined to the more rugged slopes of the lower limestone hills where they both still retain a foothold in places where the natural growth seems never to have been cleared away. But the vast majority of royal palms now in existence in Puerto Rico stand on land which has been cultivated at one time or another, and where the palms were able to secure a foothold before the competition of other plants became too strong.

The discovery of root tubercles on a young plant of this species has been noted in the introductory statement. These tubercles though small in size are very numerous upon the smaller roots. In shape they are mostly oval and symmetrical. The larger are about 2 mm. in length though our natural-size photograph shows several fusiform or clavate bodies from 5 to 10 mm. long and as much as 2 mm. thick. The color of the roots and tubercles is white.

The royal palm of Florida is commonly referred to Oreodoxa regia, though with very doubtful propriety. Apparently on account of its great size, Cooper (Smithsonian Report 1860: 440. 1861) was inclined to identify it with Oreodoxa oleracea which had also been reported from the Bahamas. The inflorescence and seeds collected by Curtis on the western borders of the everglades (no. 2676) are, however, obviously not those of R. oleracea but are much more similar to those of R. regia. The branches of the inflorescence are much longer and more lax than those of the species of Cuba and Puerto Rico, from which they also differ in the frequent development of tertiary branches, in this respect resembling Roystonea oleracea. The fruits do not resemble those of R. oleracea but are closely similar to those of the other species though somewhat smaller and more nearly spherical. Several reliable witnesses are on record to the effect that the trees are from 28 to 35 metres high and as much as 45 metres has been claimed, while among the royal palms of Cuba and Puerto Rico 18 metres is the commonly recognized limit of size. Mr. C. T. Simpson, of the U. S. National Museum, states that the palms of southwestern Florida lack the conspicuous bulge so characteristic in the trunks of the Puerto Ricon trees, and that they grow almost in reach of tide-water, while the natural habitat of the Puerto Rico species is evidently the limestone hills. In view of these differences it seems preferable to treat the Florida royal palm as a distinct species, for which the name Roystonea Floridana is proposed.

Mr. Simpson also informs me that the royal palms seen on the islands off the coast of Honduras had the size and habit of those of Florida and not the relatively stunted appearance of those seen by him in Hayti and Jamaica. This fact is suggestive in connection with the popular idea that the palms of Florida are to be looked upon as recent arrivals from Cuba. Instead it seems more reasonable to believe that the royal palm of Puerto Rico, like the species of Thrinax of that island, is a remnant of the flora of the time when the limestone hills were keys and hammocks like those of southern Florida, and relatively poor in vegetation able to crowd out the palms.

Acrista gen. nov.

Trunk slender, of uniform diameter. Pinnae horizontal, appendiculate. Inflorescences distinctly infrafoliar; spathes two, the outer short, the inner long and slender. Spadix once-branched, the branches coarse, tapering. Fruits with stigma lateral, seed deeply ruminate, embryo basal.

Related to Roystonea, but differing in the more slender habit, the once-branched inflorescence, the basal embryo, and in having the leaflets in one plane. The color of the foliage is also considerably lighter than that of the royal palm so that from a distance the general appearance suggests the cocoanut rather than the royal palm.

There is also some resemblance between the foliage of Acrista and Cocops, but the absence of sheathing leaf-bases in the latter genus will enable even young specimens to be separated. Moreover the leaf-divisions of Cocops are much narrower and those at the end of the leaf are not so much shortened as in Acrista.

Further differences from Roystonea are to be found, such as the much smaller size and the larger roots, which are tuberculate and inclined to become superficial like those of the llume palm. The sheathing leaf-bases are not as long proportionately as in Roystonea, and there is a distinct formation of fibers, although the texture is flimsy. The outer sheaths do not split off and fall away as promptly as in Roystonea but several dead ones sometimes hang from about the base of the crown. Although the sheath is longer than in Aeria the fibers are much better developed, there being but a few membranous shreds in Aeria, and no distinct fibers at all.

Among the mountains between Cayey and Guayama many summits are covered with the palma de sierra, probably in places which have never been cleared. A few of the palms follow down the steeper uncultivated ravines. From a distance the crowns suggest royal palms but a closer view renders the difference apparent. There is also no suggestion of the bulging trunk of Roystonea. In height the palma de sierra probably does not exceed the royal palm.

The tips of leaflets of young leaves are connected by two brittle red strands both of which lie on the mesial face, one along the edge, the other near the middle. The tips of the leaflets are of the same material and are sometimes persistent as long corneous appendices like those of the cultivated Howea.

The generic name Euterpe Gaertner, which is commonly applied to a considerable series of American palms related to the present, was in reality established for the Malayan genus for which the name Calyptrocalyx Blume is now in use, Pinanga silvestris globosa Rumphius being cited by both Gaertner and Blume as the original, in the one case, of Euterpe globosa, and in the other of Calyptrocalyx spicatus. The origin and identity of the seed described and figured by Gaertner have not been established, and seem likely to remain in doubt; but in describing Calyptrocalyx, Blume argued that the generic name should remain with the seeds studied by Gaertner and declared that these did not belong to any Malayan species but to some of the arecoid palms of the Mascarene Islands. This suggestion seems not to have been disposed of by Martius or others, but the fact that Gaertner’s fruits showed an apical stigma seems to exclude them from the American group with which the generic name has been associated.

In making use of the name Euterpe for Brazilian palms Martius cites Gaertner as author of the genus and states that it is of worldwide distribution in the tropics. Gaertner’s E. globosa is placed as a synonym of E. oleracea[^[5]] Martius, and Jacquin’s older name Areca oleracea stands in the same relation to Euterpe edulis Martius, thus rendering Euterpe oleracea Martius a specific homonym. Subsequently Martius claims the genus Euterpe for himself and expresses doubt whether it is the same as that named by Gaertner, while Drude in Engler and Prantl’s Natürlichen Pflanzenfamilien says “Euterpe Mart. (nicht Gaertn.).” Martius also admits that the West Indian Areca oleracea Jacquin is distinct from the Brazilian species of Euterpe, and redescribes it under the name Oreodoxa oleracea.

A further complication connected with Acrista was brought to light by finding that specimens collected by Sintenis (no. 1525) in the Luquillo Mountains in northeastern Puerto Rico and distributed from the Berlin Botanical Garden as Oreodoxa oleracea belong to the present genus, together with others collected in Martinique by Hahn (no. 805) and identified at Paris. With the last, the local name choux palmiste is given, the same which Jacquin noted in the original description of his Areca oleracea (Stirp. Am. 278. 1763). Moreover, it can scarcely be determined from Jacquin’s description whether he was dealing with a Roystonea or an Acrista or with both, though his claim that his was the tallest palm of the Antilles might hold the name for the Roystonea.

It might then be argued by some that Miller’s species, Palma altissima constituted a segregate from Jacquin’s oleracea and that the latter name is available for the Acrista of Martinique, whether identical or not with that of Puerto Rico. But with a possible doubt between the Acrista and the Roystonea there can scarcely be a justification for the use of the same name for a third South American species or a fourth West Indian.

As a means of decreasing the confusion it may be suggested that as neither the generic nor the specific name of the Brazilian palm which Martius called Euterpe oleracea (Hist. Nat. Palm. 2: 29) is available, the name Catis Martiana may be proposed, the generic designation having reference to the drooping pinnae characteristic of the present species and several of its South American relatives.

Acrista monticola sp. nov. [Plate 44.]

Trunk smooth, 10 to 15 m. high, perhaps taller, from 12 to 15 cm. in diameter, with distinct ring-like leaf-scars and internodes, light brownish or appearing grayish with bark lichens.

Leaves about 2 m. long, the pinnae lanceolate, equally spaced and lying nearly horizontal, 55 cm. long and 4 cm. broad; the surface light green on both sides, with very close parallel longitudinal veinlets, but no visible cross veins. The sheathing bases are considerably shorter and generally appear somewhat more robust than in Roystonea. In protected situations the leaf-bases persist and the margins shrivel up and expose a flimsy network of fibers. Inflorescences appearing several close together; by the falling of the leaves above them they are left several inches below the leaf-bases before maturity is attained. Spathes fusiform, long, more slender and pointed than in Roystonea. Spadix once-branched, 1 m. long, 6 cm. in diameter at base, tapering gradually to the apex. Branches 23 cm. long and less, the proximal branches longest; at first appressed to the rachis, the branches are opened out and held stiffly erect by a fleshy turgid cushion on the upper (distal) side of the base of each. The branches of the rachis may thus be said to be hinged, and with maturity the supporting cushion dries away and allows them to resume a direction nearly parallel to that of the rachis.

The dried fruits of Acrista are grayish brown in color and nearly smooth or somewhat coriaceous in external texture; they measure 11 or 12 mm. in length and are nearly as wide, being slightly oboval in shape. The outer wall is thin and brittle and covers a more or less distinct thin layer of amorphous brownish material probably representing the pulp of the fresh fruit; in the dry state this may adhere either to the outer wall or to the fibers next inside. Near the base these fibers are simple, pointed and vertical; about half way up they divide and anastomose and are, as it were, felted and cemented together to form an oval sac open below and closed above. The outer fibers are much coarser than the inner and there are sometimes suggestions of three layers separated by a dark-brown friable material. A few of the delicate inner fibers are adnate to the surface of the seed which is otherwise free from its fibrous covering.

Seed 8.5 mm. by 8 mm., slightly lighter in color than the outside of the fruit. Surface slightly uneven with obscure veinlike ridges and impressions of the fibers of the outer covering. The kernel is white, hard and bony, and deeply ruminate, though this is not apparent from the outside. The channels are very narrow and often radial and straight; they penetrate 3 mm. or less. Embryo directly basal; hilum lateral, somewhat below the level of the stigma; a short raphe extends about half way to the embryo.