RELATIONSHIPS OF THE FALSE DATE PALM. 253 
ALLIANCES WITH OLD WORLD PALMS. 
Though the relationships of the Old World and New World palms 
are still very imperfectly understood it is evident that only a few of 
the families extend over both hemispheres. The geographical limi- 
tations of the families do not appear so remarkable when the ecologi- 
cal limitations of this group of plants are considered. The palms 
grow too slowly to be able to compete with other types of vegetation 
and the large, heavy seeds are not readily disseminated. There may 
have been a palm age in some former geological epoch when the palms 
occupied a larger proportion of the land and enjoyed better facilities 
of distribution, but at the present time the tendencies are in the 
other direction. Even inside the continental areas the different 
groups of palms have local or definitely limited distributions. Thus 
only a few of the South American and Central American types have 
secured footholds on the West Indian Islands. 
The land connection between North and South America has re- 
sulted in only a slight interchange of palm floras. The Chamaedorea- 
ceae, which are so richly developed in Mexico and Central America, 
have penetrated only to a slight extent into Colombia and Venezuela 
and are practically absent from the great Brazilian region. On the 
other hand, the distinctively South American families have as little 
to show in the way of any complete occupation of the tropical regions 
of North America. This is true of the Iriarteaceae, Geonomaceae, 
Ceroxylaceae, Manicariaceae, Phytelephantaceae, and especially of 
the Cocaceae, the most numerous and highly developed of the Ameri- 
can families. None of these groups has any extra-American repre- 
sentatives, unless the coconut palm itself and the African oil palm 
(Elacis guineensis Jacq.) be considered as such.* 
The scale palms (Lepidocaryaceae) are the only family that can be 
said to have a cosmopolitan distribution. Some of the Old World 
fan palms, such as Pritchardia and Livistone, may belong with the 
American palmetto palms instead of with the Asiatic talipot palms 
(Coryphaceae). In geologic times the fan palms are known to have 
had a circumpolar distribution, which would account for their pres- 
ence in both hemispheres. 
The closest approach among the pinnate-leaved tropical types is 
between the royal palm family (Acristaceae) of the New World, and 
the betel palm family (Arecaceae) of the Old Worild. Several peculiar 
genera found on the Pacific Islands may connect the more divergent 
continental forms. Some of the American stilt palms have leaves 
that suggest those of the Old World sugar palms (Caryotaceae), but 
1 Cook, O. F. Origin and Distribution of the Coconut Palm. Contr. U. 8. Nat. 
Herb. 7: 257-293. 1901. Also History of the Coconut Palm in America. Contr. 
U.S. Nat. Herb. 14: 271-342, 1910.) 
