LEJEUNEA. 65 
badiz, globose v. oblong, pressione mutua polyhedre, tuber- 
culose.* 
The genus Lejewnea, reconstituted as above, to contain all the strictly 
monogynous Jubulew, is well distinguished ‘from Frullania by (1) the 
branches being contiguous to the outer base of the leaves, 7.¢., infra- 
axillary ; (2) the usually rhomboidal or ovate lobule being either plane or 
ventricose, but never (as in Frullania) either galeate or “inversely saccate 
—shaped like a bell or a glove finger—except in the very rare case of the 
British L. calyptrifolia and 3 or 4 allied tropical species, where the lobule 
(larger than the lobe !) is lengthened out into the shape of-a hollow 
horn or club ; (3) the monogynous ? flowers; (4) the innovations, where 
present, as they are in the great majority of the species, being adnate 
to the 9 bracts ; (5) the pedicel cruciate on the section, only 4 cells (not 
8) across, quasi-articulate when dry and mostly geniculate at the joints. 
There are other differences of minor importance. Its diagnosis from 
Jubula I have already indicated under that genus. 
It is only in the robuster species that the stem of Lejewnea is com- 
posed of many layers of nearly homogeneous cells, as in Frullania. In 
nearly all the more delicate species the cortical layer is of wider and 
more pellucid cells (oval on the section) than the axial layers. Thus, 
in L. lunulata (Web.) the stem has a distinct cortical layer of about 10 
series of large pellucid cells, whereof those of the antical and postical 
faces are broadest. The inner, or axial cells are thrice as slender, 
hexagonal on the section, and in 3 concentric layers, so that the 
whole stem is 8 cells across. In “. leta, L. et L., the stem is only 
6 cells across, the large cortical cells 7- or 8-seriate, and the thrice nar- 
rower interior cells about 30-seriate. These are typical cases. In the 
very minute species the axial cells are fewer. As the leaves are in all 
cases an extension of the outermost layer of the stem, or branch, where 
the cortical cells are larger than the inner, the texture of the leaf also 
is comparatively lax. 
While every branch is infrafoliar at its origin, neither the suprajacent 
leaf nor its collateral underleaf is at all modified by the branch, which 
may correctly be said to subtend the leaf, instead of the leaf subtending the 
branch, as in Frullania, Porella, Lepidozxia, and other pinnately-branched 
genera, where the axillary leaf is distinctly modified. 
The lowest point of the complicate leaf is the base of the fold. In two 
of the more conspicuous subgenera, Archilejewnea and Odontolejeunea, each 
leaf is inserted on the stem on two lines meeting below at an angle, re- 
sembling a narrow letter V, and diverging but slightly from parallelism 
to the axis of the stem—the lobule on the lower line, the lobe on the 
upper, and (although usually much larger) not ascending higher on the 
stem than the lobule, but at the antical base abruptly dilated and semi- 
cordate. This indeed is the typical mode of leaf-insertion throughout the 
genus, with such differences as are induced by the lobule being very much 
smaller than the lobe, or becoming obsolete, and sometimes by the nearly 
transversal insertion of the lobe on the stem. The latter character i is, 
however, very rare, and is never so marked as obtains throughout the 
genus Frullania, if we except the small subgenus Cololejeunea, where the 
* De habitatione et distributione Lejeunearum videas post subgenerum 
descriptiones. 
TRANS. BOT, SOC, EDIN. VOL. XV, I 
