7 c 
less abbreviated branch, not proliferating (so far as observed) ; bracts in two or 
three pairs, similar to the leaves when well developed, but with less obliquely 
spreading lobes and poorly developed apical teeth on the lobules, monandrous: 
capsule about 0.15 mm. in diameter: gemmae about 0.06 x 0.05 mm., composed 
(normally) of sixteen cells, each apical quadrant cutting off two segments, margin 
with five obtusely projecting cells. [Text figs. 1-9.] 
In its minute size and extreme delicacy C. tuber culata rivals the species of 
Aphanolejeunea, a characteristic example of which is noted below. The structure 
of the lobule, however, with its clearly marked teeth shows conclusively that 
the plant is not an Aphanolejeunea , and the inflated perianth with its five indis- 
tinct keels indicates that it is a true Cololejeunea. 1 Another species of Colole- 
jeunea, C. diaphana Evans, 2 which was likewise discovered by Dr. Small in sub- 
tropical Florida, is only a trifle larger than C. tuberculata and is even more deli- 
cate in structure. C. diaphana has recently been recorded from Porto Rico by 
the writer, and it is probable that C. tuberculata also will be found in the West 
Indies. 
One of the most striking features of the present species is the conspicuous 
roughness of the leaves and perianths. This is due to the development of a pro- 
jection or tubercle on each cell of the lobe, and on each cell of the perianth except 
in the basal region. Even the cells of the lobules are more or less affected; on 
ordinary leaves and on the male bracts the tubercles are restricted to the neigh- 
borhood of the keel, but on the perichaetial bracts they sometimes occur on all 
the cells. In the tubercle the entire outer wall of the cell is involved, but the 
projection narrows to a rounded apex; here the wall exhibits a conspicuous thick- 
ening, which sometimes occupies about half the length of the entire tubercle. 
Roughness of the leaves is of widespread occurrence in the genus Cololejeunea 
and seems to be always due to projecting cells, but these are rarely so pronounced 
or so abundant as in C. tuberculata. There are, however, a few species which 
equal or even surpass C. tuberculata in roughness. One of these is C. Rossettiana 
(Massal.) Schiffn., a local European species now known from Italy, France, and 
the British Isles. In this remarkable plant, which is considerably larger than the 
new species from Florida, the tubercles show much the same structure, but they 
are found on all the cells of the lobules of ordinary leaves as well as on the cells of 
the lobes, and the apical thickening of the wall is sometimes more than half the 
length of the entire tubercle. 
Among the species of Cololejeunea known from the United States the only 
one which resembles C. tuberculata very closely is C. Biddlecomiae (Aust.) Evans. 
This plant has a wide distribution from New England westward to Wisconsin and 
southward to Florida and Alabama. Although a small species it is not so minute 
as C. tuberculata, the leaves being about 0.35 mm. in length and the perianths 
measuring about 0.6 x 0.35 mm. In C. Biddlecomiae the ovate lobes narrow 
toward the apex, which may be obtuse or acute; the surface of the lobes is rough- 
ened from projecting cells, and the margin is denticulate or crenulate; the apical 
: For a discussion of the genus Cololejeunea and allied genera, see Evans, Bull. Torrey Club 
38 : 251-286. pi. 11, 12. 1911. 
2 Bull. Torrey Club 32 : 184. pi. 5, f. 9-14 . 1905- 
