12 THE GENUS PHORADENDRON 
tropical species as P. chrysocarpum, said to have white or yellow berries 
when fresh, have the fruit represented in the herbarium with a dull 
leathery looking surface, the epidermal cells of which have a brassy glint 
as on other young parts of these plants. The pulpy red berries of P. 
rubrum, more or less blackened when dry, are distinctly reticulate under 
a lens by the outlines of their small epidermal cells, and if, as in P. com- 
mutatum, these are convex, a velvety-dullness is imparted by them to 
the surface. P. emarginatum and its allies, as well as P. Eggersii and 
a few other tropical species, have the surface of the fruit distinctly 
warty: such warts may be more or less confluent into wrinkles, and in 
P. Grisebachianum the pulp becomes very deeply wrinkled. This sug- 
gests a range of characters as yet to be made out with sufficient certainty 
for safe application as differential. Another fruit character that will 
doubtless prove of much taxonomic value should be derived from the 
seed and its investing coat of fibres (Pl. 10), between which and the 
outer skin lies the mass of viscid pulp for which mistletoes have long 
been known: in shape and size this appears to differ considerably when 
different species are compared, but its utilization must rest on compara- 
tive study of the mature fruits of many species. In most species the 
ripe fruit is globose, often varying into ellipsoid as in some of our south- 
ern mistletoes, or egg-shaped, as in P. chrysocarpum,—depressed and 
elongated modifications of these forms being frequent. Sometimes, but 
it is hard to tell how constantly or characteristically, a short neck with 
sub-parallel sides is noticeable, as in P. californicum (Pl. 8). Rarely, 
as in P. acinacifolium and its allies, the fruit is distinctly elongated, the 
ellipsoid or ovoid fruits of other groups being not much longer than thick, 
and in P. trinervium, which ultimately has nearly globose berries, the 
partly matured fruit is similarly lengthened. Usually the berries are 
glabrous, but in some of our western species they or their sepals are 
somewhat hairy ; and P. Robinsonii, P. Palmeri, and a few other tropical 
species, have retrorsely hirsute berries. When the fruit of P. villosum 
is compared with that of P. flavescens, the sepals with which the berry 
is crowned are seen to be ascending and somewhat separated in the 
former, but closely inflexed and meeting in the latter,—a difference 
rvable everywhere, the erect or widely parted sepals of such species 
acinacifolium, P. trinervium and Р. Eggersii being especially 
able (Pl. 8, 9). 
SCALES.—One of the characters most available and significant in the 
. Classification of the species of Phoradendron is a fundamental difference 
in their leaves. By far the larger number of species have unmistakable 
foliage, but our western group to which P. californicum and P. juniper- 
inum belong have their leaves reduced to short thin scales (РІ. 4) which 
resemble those of the related genus Arceuthobiwm or Razoumofskya so 
