556 ROBINSON: POLYCODIUM 
In the Vaccinium group as a whole there is a transition in this 
respect, and Polycodium is merely one case of many. In certain 
species, such as V. caespitosum Michx., V. scoparium Rydb., and 
V. Myrtillus L., the flowers are few in number on a branch borne 
in the axils of what are apparently quite normal leaves as to size, 
shape, and texture. In others the inflorescence is quite clearly 
racemose, or by contraction fasciculate, the pedicels subtended 
by bracteoles quite different in appearance from the vegetative 
leaves. This includes nearly all the species of the eastern United 
States. There is yet a third group, which almost perfectly links 
the two, the inflorescence being perhaps best described as a leafy 
raceme. These are mostly tropical plants. Incidentally, these 
three groups follow rather closely the lines indicated by the 
stamens. 
In the case of Polycodium there is a group ‘‘in which,” to use 
Nuttall’s expression* when describing Picrococcus floridanus, ‘the 
flowers appear truly axillar.”” Here also belong the names Polyco- 
dium caesium Greene, P. oliganthum Greene, and P. revoluium 
Greene. Nuttall’s type seems to have perished, which will cause 
trouble to those who believe this group to contain more than one 
species, for he has no sufficient description for more definite deter- 
mination. In the case of the other species duplicates of the type 
collections have been examined, and there seems no sufficient reason 
for holding them distinct. In separating P. revolutum from P. 
caesium Professor Greenef relies chiefly on the leaves of the former 
being more pubescent, more oval and obtuse, their margins 
revolute, the calyx lobes deeper, acute or acuminate instead of 
scarcely acute, and deeper corolla lobes. It is not possible to 
separate the series of specimens on these characters or any of them, 
not even 
those drawn from the leaves being especially unreliable, 
holding for the collections on which the species were based. There 
seems even less reason for segregating P. oliganthum. ‘ 
Now, the same thing happens in Polycodium as 1n se a 
cinium group in general; the leaves, in the axils of whic a 
. . . b e 
flowers are borne, are often reduced in size but still retain the ot 
: . . 2 
characters of the typical leaves of the plant; yet again, they may 
* Trans. Am. Philos. Soc. Il. 8: 262. 1843. 
t Pittonia 3: 249, 250. 1897. 
