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.