REPORT FOR 1907. 
3T'5 
of the river, but is somewhat difficult of access even at low tide 
owing to the mud banks which surround it. After examining a large 
number of specimens in situ and comparing it with its associate, 
S. iriqueter^ which, however, occurs in much less quantity, we are 
convinced that it is a hybrid {S. lacusiris x triqucter)^ as suggested 
by Rev. E. F. Linton (‘ Journ. Bot.,’ 1907, 301). The stems are 
always taller than S. triqueter but more slender than S. lacusiris, the 
lower part round, the upper part obtusely triangular. In extreme 
forms which approach S. lacusiris we observed that the stems 
in the upper half were only very slightly angled with very obtuse 
sides, or nearly round, but never quite circular as in the common 
bulrush, S. lacusiris. Other plants evidently nearer S. iriqueier have 
stems triangular from the base, with occasionally one angle sub-acute, 
leaves with or without lamina, inflorescence compact or with the 
spikelets on elongated branches and evidently pedicelled ; hypo- 
gynous bristles mostly equalling the ovaries, anthers glabrous or 
shortly ciliate, styles 2 or 3. Pollen often ill developed. The 
essential characters of the hybrid and assumed parent may be 
contrasted as follows ; — 
.S’, triqueter. 
Flowering stems acutely 
triangular about 3 ft. 
high. 
Leaves reduced to a 
sheath, lamina not 
developed. 
Spikelets two to many, 
sessile, and compact 
at the apex of elon- 
gated branches. 
Ilypogynous bristles 
ecpialling or a little 
shoi'ter than the nut. 
Anthers glabrous. 
.Styles 2. 
S. carinatus. 
Flowering stems terete 
below, obtusely tri- 
angular above, 3 — 6 ft. 
high. 
Leaves with or without 
lamina. 
Spikelets varying in 
number, sessile, or on 
elongated branches. 
Ilypogynous bristles 
mostly equalling the 
ovaries. 
Anthers glabrous or 
shortly ciliate. 
Styles 2 — 3. 
S. lacusiris. 
Flowering stems stout, 
terete 6 — 10 ft. 
Leaves with lamina more 
or less developed. 
Spikelets never sessile, 
often long pedicelled. 
Ilypogynous bristles 
equalling or slightly 
exceeding nuts. 
Anthers fringed at apex. 
I Styles 3. 
The character of the nuts we do not mention as nearly all 
the spikelets of S. iriqueier and S. catinaius were found to be 
barren. In the case of A. iriqueier this sterility may have been 
due to an abnormal season. Jackson found well-developed nuts 
in one or two spikelets of S. carinaius, and these were convex 
on the back, as described in Babington (‘ Manual,’ Ed. IX., 450), 
and quite different in shape from those of X. lacusiris, correctly 
described as bluntly trigonous. Some forms of this hybrid bulrusli 
much resemble S. lacusiris, but they are always more slender than 
