164 Rhodora [SEPTEMBER 
River, Cape Breton (1445). The other Nova Scotia records for 
the species, also made by Nichols, represent the closely related N. 
subelliptica Lindb. and will be considered in another connection. No 
material from Greenland has been available for study, but the pub- 
lished records, made by the Danish botanist, C. Jenseri,! are undoubt- 
edly trustworthy. Unfortunately, our knowledge, even at the present 
time, is not always sufficient to render a positive verdict in the case 
of sterile and aquatic material, in spite of the attention which Schiffner 
and other European students have given to modifications induced 
by an aqueous environment. 
The general habit of N. obovata is not unlike that of N. obscura; 
the older stems cling to the substratum, while the younger stems are 
free or nearly so. "There is therefore a tendency for the rhizoids to 
be restricted to the older stems and to the stolons, which are usually 
produced in abundance. "The branching is the same as in the two 
preceding species, but no subfloral innovations have been observed 
even in the absence of fertilization. The color of the plants is origi- 
nally a deep dull green, but brownish or reddish pigmentation is often 
present, and in extreme cases a distinct crimson hue becomes apparent 
in transmitted light. The plants never show the deep purple color 
which is often associated with N. obscura. "The rhizoids are usually 
red but may be pale or even colorless; no tendency to form a ventral 
bundle is to be observed. 
The leaves (Figs. 10-12) are distant to loosely imbricated and are 
about as large as those of N. hyalina. From a long series of measure- 
ments the length was found to be between 0.75 and 1.17 mm. and the 
width between 0.7 and 1.55 mm. There is a tendency for the leaves 
to be a little longer than broad, but many of the leaves measured 
were as broad as long and a few were even broader than long. In 
most cases the shape might be described as broadly ovate with a 
rounded apex. "The line of attachment is normally oblique but some- 
times the obliquity is slight and a subtransverse attachment is 
approximated, especially in the dorsal part. In this respect it often 
exceeds the condition found in N. obscura. At the dorsal base the 
leaves are decurrent, sometimes for a considerable distance; at the 
ventral base the decurrence is often equally distinct. In what may 
be regarded as the most typical cases, the leaves spread widely and 
1 Meddel. om Grønland 15: 381. 1897; 30: 309. 1906. 
