ORIGIN—RANGE OF SPECIES 15 
extends around the earth in the warmer zones, reaching well toward the 
limits of the cool-temperate latitudes in both hemispheres. Increasing 
knowledge of its forms has gradually led not only to the segregation of as 
markedly different genera as Viscum and Phoradendron, Loranthus and 
Psittacanthus, ete., but to recognition that nearly all of the genera are 
exclusively either of the New World or of the Old World—the most 
marked exception being the small and simple genus Arceuthobium or 
Razoumofskya, with American, European and Asiatic species. 
These facts point to anything but a recent migration of American 
and European stocks from the original center of distribution; at the 
same time they do not point to a very ancient origin for our own genera. 
Perhaps because of their very common occurrence in upland regions— 
though P. flavescens, for instance, тау be found in the greatest abun- 
dance on trees in swamps or river bottoms—and even more beeause of 
their generally fleshy substance with relatively little lignifieation, our 
mistletoes have scarcely left fossil remains, one Tertiary species, only, 
P. fossile of Eeuador, being recorded as thus far recognized in the genus 
Phoradendron. Everything considered, the genus may be regarded as 
probably of late Tertiary origin in the New World. When and where 
on this continent its two primary subdivisions came into existence will 
make a fascinating subjeet for future study. 
RANGE OF SPECIES 
In the geographie distribution of its species, Phoradendron is rather 
unusually instructive. The genus is strictly American and extends from 
Washington, Southern Colorado, the mouth of the Ohio River and South- 
ern New Jersey to the mouth of the La Plata on the continent, and 
through the entire West Indian chain: one species occurs in the Pacific 
island Guadalupe, and two are found in the Galapagos group of Pacific 
islands—both oceanic but with American floras. None of its many spe- 
cies of fairly homogeneous character possesses a very wide geographic 
range. Marked examples of wide-spread occurrence are afforded only 
by such polymorphous species as what is usually called P. latifolium, or 
an assemblage of intricately related if differentiable species like that 
usually known as P. rubrum or P. quadrangulare, which range from 
Brazil to Central Mexico and well through the West Indies. Few spe- 
cies, indeed, equal in absolute range our native P. flavescens, which occurs 
from southern New Jersey to the lower Wabash, Oklahoma and eastern 
Texas, reaching southeast to the gulf and ocean. 
Admirably endowed with means of free dissemination through their 
berries with extremely viscid pulp, which leads to their dispersal by 
birds, these mistletoes seem limited nevertheless to a surprising extent by | 
