14 THE GENUS PHORADENDRON 
species remain to be noted and observers and collectors who interest 
themselves in the genus in the future will do well to pay particular atten- 
tien to this point. 
So far as I know, none of the representatives of this genus attack 
either tree ferns or Monocotyledons, and relatively few are found on 
Conifers: the majority affect woody Dicotyledons. Though sometimes, 
as in the case of our common mistletoe P. flavescens, occurring on a num- 
ber of unrelated hosts, most of the species appear to be restricted in 
this respect, though to what extent is to be shown, rather than inferred 
from the seanty information now at hand. , The oak, known іп еоппес- 
tion with the European mistletoe rather from its infrequeney as a host 
than because it is often seen to support the parasite, is one of the most 
frequently attacked trees on our own continent except in the Northeast; 
and in the Southwest the sycamore, mesquite, cottonwood, hackberry 
and elm are much parasitised. Though the European Viscum sometimes 
occurs on Conifers, these trees, which support the related genus Arceutho- 
bium or Razoumofskya in abundance, appear to be attacked by only a 
limited number of species of Phoradendron which constitute a well- 
limited group, the ‘‘Pauciflorae,’’ and this group is strictly confined to 
Conifers except for one species, P. californicum, which affects a variety 
of Angiosperms but no Gymnosperms, and P. Bolleanum which, in addi- 
tion to coniferous hosts, has been collected on Arbutus. The succulent 
Cactaceae support one species, P. Kuntzei. 
Secondary parasitism is not at all unknown in the genus, though re- 
stricted to its tropical species, one group of which, the ‘< Amplectentes, ”? 
exhibits this trait markedly. Except when they serve as hosts for other 
mistletoes, the Phoradendrons do not appear to suffer much from the 
attacks of parasites. I have seen a single collection (P. antillarum) 
in which a mistletoe was overgrown by Cuscuta. Few fungi are known 
for them even when dead ;* and the number of insects known to attack 
them is very limited,t though some southwestern collections are badly 
infested by scale insects. 
ORIGIN OF THE GENUS 
Questions as to the origin of families like the Loranthaceae are doubly 
difficult because complicated by parasitism and attendant reduction. Of 
a group of families with little-differentiated ovules and seeds which Van 
Tieghem has brought together under the name ‘‘Inséminées,’’ the Loran- 
thaceae give every indication of tropical Asiatic origin, and the family 
“СУ. Saccardo, Sylloge Fungorum,—host index.— The related genus Arceuthobium 
is likewise free from fungi.—Cf. Weir, Journ. Agr. Researeh. vol. 4. p. 369. 
ҰСУ. Schwarz, Proc. Entomol. Soc. Washington. vol. 4. p. 397. 
