Palms of Puerto Rico 547 



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 be- 

 tween Bayamon and Arecibo. 



Key to the Geiier* of Arecaceae 



Trunk tall and slender, tapering from a swollen base ; spathes numerous (7) ; inflores- 

 cence 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 I 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, stand- 

 ing close to the leaf-bases. Roystonea. 

 Trunk slender, of uniform diameter ; leaf-divisions at equal distances, hori- 

 zontal ; inflorescence once-branched, at maturity 15 cm. or more below the 

 leaf-bases. Acrista. 



Aeria gen. no v. 



A tall slender palm evidently related to Gaussia, but the em- 

 bryo lateral instead of basal, and the pinnae without basal cush- 

 ions. 



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 inter- 

 foliar 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. 



