8 THE GENUS PHORADENDRON 
Stem.—Though it frequently happens that only one of the two 
opposed buds at a node develops into a branch, so that a pseudodicho- 
tomous forking may appear, the greater number of species, including 
all of those in our own flora, are monopodial or percurrent in their 
growth; but a comparison of P. flavens and P. racemosum, for example, 
among the West Indian species, shows that in the former the pereurrent 
growth is very constant, while in the latter the main axis is so rarely 
continued that forking, or, through accessory development, fasciculation 
of the stems is all but the universal rule. In P. cymosum and a group 
of related species the suppression of the main vegetative stem is further 
accentuated through its replacement by a flowering spike, so that the 
seeming dichotomy of P. racemosum is here replaced by a eymose forking. 
While all of our own species have a terete or nearly terete stem, 
squarish in some of the mountain forms, such a species as P. vernicosum ' 
presents the phenomenon of its compression into an elliptical cross sec- 
tion below the nodes; in P. carneum, ete. it is sharply 2- keeled: in P. 
peruvianum, ete., it is convexly sword-shaped, and it becomes 2- winged 
in P. dipterum or even very thin and broad in P. platycaulon. P. rubrum 
and many other species have a comparable sword-like compression 
accompanied by a rhombic keeling of the broad surface, with extremes 
from little to marked widening reaching its culmination in the very 
broadly winged stems of the Mexican species which Hooker mistook for 
Viscum falcatum (РІ. 62, 63). P. trinervium and a number of other 
tropical species have this rhombic keeling amplified into a sharply and 
nearly equally 4- angled character, which in P. tetrapterum and a few 
others develops into a strong and often undulate winging. As a rule 
these stem peculiarities are most evident on the uppermost internodes 
of a branch; sometimes they disappear entirely as the stem ages, or are 
represented by a faint lining on otherwise nearly or quite terete older 
internodes: in one species, P. paradoxum, terete-based and aneipital 
internodes regularly alternate in the branches. 
Lrar.—lIf, as is the case, leaf-form in this genus varies in the same 
species or even on the same branch so greatly as to prevent its use with 
precision for the differentiation of closely related forms, and though 
identical shapes may be presented by the leaves of species not at all 
related, the foliage of a given species comes with familiarity to present 
a collective effect that is characteristic so far as it goes. Knowledge of 
the species when growing is certain to reveal very marked differences 
in texture, veining, and direction of the leaves which are lost or uncertain 
in the herbarium; but even in dried specimens many foliage charac- 
ters may be picked out. In P. Eggersii and a relatively small number 
of other species, distinct clean cut petioles are found, while іп 
