AMERICAN 
JOURNAL OF BOTANY 
Vol. II May, 1915 No. 5 
THE MORPHOLOGY AND SYSTEMATIC POSITION OF 
PODOMITRIUM 
Douglas Houghton Campbell 
The present classification of the thallose Jungermanniales ("Ana- 
crogynae" of Leitgeb) is very far from satisfactory, as our knowledge 
of the morphology of several genera is still very fragmentary. 
The genus Podomitrium, with which the present paper is concerned, 
comprises two known species, P. Phyllanthtis of the Australasian region, 
and P. Malaccense, which Stephani^ states has been reported hitherto 
only from Singapore and New Caledonia. Stephani unites Podomit- 
rium with Umbraculum to form the genus Hymenophytum, but there 
seems to be ample reason for separating the two genera. 
In the spring of 1913 the writer collected at several places in Sara- 
wak, in Western Borneo, abundant material of P. Malaccense, which 
is a common liverwort of this region, and it was also found at a single 
station in Luzon, Philippine Islands. It is highly probable that the 
plant will be found in the Southern Philippines also, but, as the sterile 
plants are indistinguishable from a Blyttia, it cannot be certainly 
recognized except when fertile. 
Podomitrium Malaccense grows upon the ground, usually upon clay 
soil, and, when it was first collected by the writer, it was supposed to be 
a species of Blyttia, which it exactly resembles except for the special 
fertile branches developed from the ventral side of the thallus. In 
the species under consideration the thallus is usually very unsym- 
metrical, one wing being almost completely suppressed (figs, i, B\ 
2), A). The conspicuous midrib bears upon its lower surface numerous 
^ Stephani, F. Hymenophytum Malaccense St. Species Hepaticarum — Mem. 
Herb. Boiss. 11, 1900. 
199 
