1923] | Evans,—Notes on New England Hepaticae, —XVII 93 
may be no signs of apical teeth, and a long series of intermediate 
conditions may sometimes be found, even on a single individual, be- 
tween this extreme and a three-toothed apex with sharp teeth sep- 
arated by obtuse sinuses. "The three-toothed condition, however, is 
rarely realized, most plants showing only one or two teeth, and these 
may be blunt or otherwise indistinct rather than acute. The leaf-cells 
average about 27 X 25 y in the middle of the leaf; their walls are 
thin, and their trigones are small and often indistinct, usually with 
straight or slightly concave sides. The cuticle seems to be smooth 
throughout. 
The underleaves are almost as variable as the leaves. They are 
distant to approximate and may be slightly imbricate in the vicinity 
of ihe shoot-apices. Sometimes they are subappressed, but it is 
much more usual for them to spread more or less widely from the 
axis. On well-developed plants they usually measure 0.2-0.3 in 
length and 0.3-0.45 mm. in width, the shape being broadly quadrate- 
orbicular. The base is almost straight and shows no indications of 
auricles; while the straight or slightly bulging sides are usually entire, 
although vague crenations or sharper teeth may be present in rare 
instances. The broad and truncate apex may show four rounded or 
obtuse teeth separated by distinct sinuses. In most cases, however, 
the teeth are fewer or lacking altogether, the apex then being entire 
or slightly emarginate. 
Although the perianths of B. denudata are still unknown, female 
branches with unfertilized archegonia are not infrequent. Branches 
of this character were detected by Gottsche, who described the 
involucral leaves as ovate-cordate and crenulate at the apex with one 
or two teeth. Unfortunately the bracts and bracteoles of B. tricrenata 
and its allies do not attain their full size and development unless 
perianths and sporophytes are produced, so that Gottsche's account 
must not be accepted without reservations. 
The most striking features of B. denudata are due to the production 
of caducous leaves and underleaves, and it is very unusual to find a 
patch of specimens in which this habit is not more or less in evidence. 
The throwing off of the leaves begins abruptly in most cases and then 
continues without interruption for a considerable period. Although 
in all probability the production of these leaves eventually brings 
the growth of the plant to an end, it is not unusual for an axis to 
fork two or three times after the caducous habit has been initiated. 
