528 Cook : A Synopsis of the 



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 inter- 

 est 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. 



The field notes, specimens and a considerable series of illustra- 

 tions for publications of the Department of Agriculture were se- 

 cured during two visits to Puerto Rico, the first in November and 

 December, 1899, the second in June and July, 1901. The pho- 

 tographs are the work of Mr. G. N. Collins. 



Key to tlie Families 



Leaves fan-shaped ; branches of inflorescence subtended by spathes. 



Family Sabalaceae, p. 529. 



Leaves feather- shaped ; spathes few, not subtending the branches of the inflorescence. 



Leaf-divisions v-shaped in section, concave above ; trunk rough with leaf-bases or 



prominent diamond shaped scars. Family Phoenicaceae, p. 528. 



Leaf-divisions inverted v-shaped in section, convex above; trunk smooth or the 



leaf-scars ring-like and not prominent. 



Leaf-bases long-sheathing, green and fleshy, finally split down the side oppo- 

 site the midrib permitting the leaf to fall; fruits with fleshy, fibrous or woody 

 endocarps. Family Arecaceae, p. 546. 



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. PI. 1 1 88. 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 



