Leaf-bases sheathing only while young, with maturity separating, except at the midrib, into a dry fibrous network which must tear or decay before the leaves fall; fruits with a stony endocarp perforated by three foramina.
Family Cocaceae, p. [558].
Family PHOENICACEAE
This family contains a single genus of old-world palms usually associated with the fan-leaved series, and differing from all other feather-palms by having the concave side of the leaf segments turned upward.
Phoenix dactylifera Linn. Sp. Pl. 1188. 1753
The date palm was probably introduced into Puerto Rico in the early part of the Spanish occupation of the island, and isolated trees are to be found in many localities especially in the vicinity of the larger towns. The climate is, however, too cool and too moist to permit the fruit to ripen properly, and there is apparently no inducement for planting in large quantities.
Family SABALACEAE
Although forming no conspicuous part of the palm vegetation of the island the fan-leaved species seem to be more numerous than those of any other family. It is certain also that further species remain to be discovered, since in addition to the species listed below, young inflorescences supposed to belong to a Copernicia were collected by Sintenis (no. 6512) near Utuado, and he also collected two other Thrinax-like palms of doubtful identity, one near Cabo Rojo and one at Fajardo.
Key to the Genera of Sabalaceae
Leaves depressed in the middle, with a distinct decurved midrib; a slender fiber rising from each of the notches which separate the leaf segments.