CHARACTERS—INFLORESCENCE, FRUIT 11 
arrangement of the flowers on a given spike present equally charac- 
teristic differences, but with the qualification that flowers of the upper- 
most joints may be fewer in number and simpler in grouping than be- 
low, while one or two of the lowest joints may be partly or entirely with- 
out flowers,—the lowermost almost universally being reduced to a sterile 
peduncle. The greater number of tropical species differ from those of the 
north in being androgynous through the occurrence of a number of 
staminate flowers on spike-joints that are otherwise pistillate, or, less 
commonly—and sometimes differentiated by the term ‘‘gynandrous’’, 
through the occurrence of a few pistillate flowers on otherwise staminate 
joints, as many of Eichler's accurately drawn plates show very beauti- 
fully. Except'in a broad way, these differences do not appear to be 
practically applicable in contrasting species, though representing in part 
morphological differences of fundamental taxonomie value. 
The prevailing grouping of the flowers is in 2, 4, or 6 series on each 
joint of the spike, 2. e., in 1, 2, or 3 ranks over each of the two scales by 
which it is subtended. Examples of the first and last are given by P. 
laxiflorum (2), and Р. flavescens (6), and where the joints are unisexual 
these numbers commonly prevail, though four series may be found by 
reduetion and as many as ten by inerease when the number is typically 
six. When the joints are androgynous, the staminate flowers often occur 
at top between the normal ranks over each seale, and this eondition is 
usually accentuated on luxuriant spikes and sometimes on all by the 
downward intrusion of a partial or eomplete third series over each seale. 
For the separation of the groups into which species fall, I have found it 
most convenient to use the prevalence of 2 or 6 series of flowers on the 
joint as a differential, providing as an intermediate the prevalence of 
the interjected two series under the designation 44-2. А glance at P. 
domingense (2), P. trinervium (4 or 4--2), P. hexastichum (6) and P. 
Lindavianum (6 to 10) will make these distinctions evident,—more than | 
6 ranks being very unusual except in some tropical species with leaves 
venulose above and dull beneath, and in some of our northern forms. 
Fruit.—Unfortunately the mature fresh fruit of few species is suf- 
ficiently well known to make its description satisfactorily possible, and 
species that are now widely separated or brought into juxtaposition may 
come to rest elsewhere when subjected to the test of this character. The 
mistletoes with which we are acquainted in our eastern woods or which 
eome to our Christmas market owe their attraetiveness to translucent 
white berries (Pl. 24), sometimes shaded greenish yellow or ereamy,— 
a eolor often changing in drying for the herbarium into a sometimes 
seemingly glaucous blue-black, as appears to be the case with such of the 
tropical species as have elear white fruit. In contrast, the desert mistle- 
toes, P. californicum, and its conifer-inhabiting allies (Pl. 4), produce 
honey- or straw-colored berries, more or less tinged with red, and such 
