— 68 — 
parts of the stem often cling closely, but the younger parts tend to be ascending 
or suberect, so that no rhizoids are to be found in the vicinity of the tips. Some- 
times, especially in the case of slender branches with distant leaves, this con- 
dition is intensified and the axis will be free from rhizoids as far back as the sixth 
pair of leaves or even farther. As Howe has pointed out, “the leaves are some- 
times slightly more decurrent ” in N. rubra than in European forms of N. crenu- 
lata. This appearance of greater decurrence is due in part to the fact that the 
lines of leaf-attachment are often less oblique in N. rubra and might even be 
described as subtransverse in certain cases (as in Fig. 4), if the decurrent por- 
tions were left out of account. From these lines of attachment the leaves usually 
spread widely, but owing to their strong concavity they often present the appear- 
ance of clasping the stem (see Figs. 1-3). In N. crenulata these conditions are 
scarcely apparent. The leaves are not only more obliquely attached but they 
are less concave and spread less widely, so that the whole shoot often appears 
laterally compressed. In the male bracts of N . rubra, as would be expected, 
the appearance of clasping is especially pronounced (Figs. 5 and 6), but the 
bracts still spread distinctly from the axis. In N. crenulata, as shown clearly 
by Muller, the degree of spreading is less and the appearance of lateral com- 
pression, -already noted in the vegetative shoots, is still to be found. The bracts 
of N. crenulata are further distinguished by their revolute margins, a condition 
not found in N. rubra. Muller notes the fact that the male plants of N. crenu- 
lata appear more delicate than the female. In N. rubra the male plants are 
often fully as robust as the female, but exceedingly slender individuals some- 
times occur, one of which is shown in Fig. 6. Aside from the small size of the 
leaves and bracts these slender plants show few distinctive features. 
In both N. crenulata and N. rubra very shallow perigynia are- developed 
and the perianths are essentially alike. The latter organs (Figs. 1-4) are nar- 
rowly to broadly ovate or obovate in outline and are sometimes laterally com- 
pressed. In the upper part four distinct folds are commonly present. At the 
contracted mouth a short beak may or may not be developed. The cells of 
the perianth are elongated in the region of the mouth, those bounding the open- 
ing projecting as crenulations or very short cilia. On the inner surface some 
of the cells often project slightly in the same way. 
The sporophytes apparently yield no differential characters. According 
to Douin 1 the structure of the stalk is very uniform in N. crenulata, showing (in 
cross section) three concentric rows of cells, the outermost composed of sixteen, 
the second of eight, and the innermost of four. Muller gives sixteen to eighteen 
cells for the outermost row and eight to twelve for the second, so that the num- 
bers are evidently more variable than Douin implies. In a section cut from a 
stalk of N. rubra (Cathlamet, Washington, Foster 512), the outermost row showed 
nineteen cells, the second nine, and the innermost six, numbers which indicate 
a similar variability. The cells of the capsule valves have been measured in 
both species and are essentially alike, those of the outer layer averaging about 
1 Bull. Soc. Bot. France 50 : 369. pi. 6,f. 8. 1908. 
