7 
Evans . — Branching in the Leafy Hepaticae. 
leaf is never coalescent with the underleaf. The latter is not essentially 
different in form from other underleaves, except that it frequently bears 
a small tooth at about the middle of its anodic edge. The first leaf of the 
branch is completely covered over by the incomplete stem leaf; it shows 
a well-developed lobule, usually in the form of a water-sac, but the dorsal 
lobe is very narrow and short, scarcely exceeding the lobule in length. 
The following leaves and underleaves are normal in structure and exhibit 
a gradual increase in size, rarely, however, becoming as large and as highly 
differentiated as the leaves and underleaves of the stem. 
The modifications noted in F. Asagrayana are less striking than in 
certain other species of Fmllania , and the remarkable F. acaleata , of western 
South America, may be chosen to illustrate a more pronounced specializa- 
tion. In this species (Fig. 7 ) the 
first underleaf of the branch is 
divided to the very base. The 
anodic division is in the form of 
a slender subulate lamina, but the 
kathodic division is a well-formed 
water-sac, similar in all respects 
to those found on normal leaves. 
This water-sac, from its position, 
looks very much as if it belonged 
to the incomplete leaf, which covers 
over the base of the branch. The 
first leaf of the branch has a lobule 
in the form of a water-sac, just as 
in F. Asagrayana , but the dorsal 
lobe, instead of being a lamina, is 
also a water-sac of the same type. The development of three water-sacs 
at the base of a branch, where in most species a single one is found, is 
apparently associated with a more xerophytic habit. The condition 
seems to be especially frequent in species belonging to the subgenera 
Meteoriopsis and Diastoloba . 
Although in the two species just noted the first segment of a branch 
forms no appendicular organs except the first underleaf, Leitgeb (’75, p. 25 ) 
calls attention to the fact that in some species it often forms in addition 
short lobe-like appendages, which grow out between the underleaf and the 
incomplete leaf. These appendages, which are exceedingly variable even 
on an individual plant, are of considerable interest and help to explain certain 
peculiar structures found in other genera. 
Lepidozia. — Only the subgenus Eulepidozia will be considered here, the 
discussion of Microlepidozia being deferred until the Microlepidozia type of 
branching is described. The common and widely distributed L . reptans , of 
Fig. 7. Frullania aculeata. Galapagos Islands 
(A. Stewart, No. 2770). x 17. 
