CHAEACTEES INFLOEESCENCE, FBUIT 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 taxonomic value. 



The prevailing grouping of the flowers is in 2, 4, or 6 series on each 

 joint of the spike, i. 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 P. flavescens (6), and where the joints are unisexual 

 these numbers commonly prevail, though four series may be found by 

 reduction and as many as ten by increase when the number is typically 

 six. When the joints are androgynous, the staminate flowers often occur 

 at top between the normal ranks over each scale, and this condition is 

 usually accentuated on luxuriant spikes and sometimes on all by the 

 downward intrusion of a partial or complete third series over each scale. 

 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 4-4- 2. A glance at P. 

 domingense (2), P. trinervium (4 or 4+2), P. hexastichum (6) and P. 

 TAndavianum (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 

 come to our Christmas market owe their attractiveness to translucent 

 white berries (PI. 24), sometimes shaded greenish yellow or creamy, 

 a color 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 clear white fruit. In contrast, the desert mistle- 

 toes, P. calif ornicum, and its conifer-inhabiting allies (PL 4), produce 

 honey- or straw-colored berries, more or less tinged with red, and such 



