240 CLIV. ERIOCAULEZ (BROWN). [ Hriocaulon. 
ovate, acute. Stamens 6; anthers black. Capsule } lin. in diam., 
trigonous. Seeds ellipsoid, obtuse at each end, light brown, nearly 
smooth, but with an opaque surface.—Durand & Schinz, Conspect. Fi. 
Afr. v. 502; Ruhland in Engl. Jahrb. xxvii. 75. Z. limosum, Engl. & 
Ruhland, and Z. Schweinfurthii, Engl. & Ruhland in Engl. Jahrb. 
xxvil. 74. 
Upper Guinea. Niger Territory: Nupe; nearly submerged in pools in 
swamps at Jeba, Barter, 1021! 
Wile Land. British East Africa: Dar Fertit; in the Biri River, Schwein- 
furth, ser. iii. 244! Jur; at Agada, near Jur Ghattas, Schweinfurth, 2476! 
After repeated dissection I am quite unable to find any definite character whereby 
to distinguish Z. bifistulosum from E. Schweinfurthii ; the heads of the latter are 
rather larger and darker than those of E. bifistulosum, and the peduncles appear to 
be stouter in the dried state, but thin transverse sections swollen out in water 
exhibit no difference in character or size. Such difference as is observable between 
them I believe to be due to vigour of growth and perhaps some difference in the food 
supply. The flowering bracts appear to be sometimes entirely glabrous, although 
usually those in the centre of the heads possess some hairs, which are easily over- 
looked. The hairs may be very deciduous, or the variation in pubescence and in the 
length of the peduncles may depend upon the depth of the water in which the plant 
grows submerged, Schweinfurth’s 2476 appears to have grown in shallow water, it 
is less vigorous than the other specimens and the stem below the leaves is very short 
or almost wanting in the examples seen, but I cannot find any real structaral 
difference, Sometimes the female flowers are all in the central part of the head and 
the males outside, in other examples the female flowers are central and the males 
outside. EE. bifistulosum and EL. limosum were both founded upon Barter’s 1021. 
It is not improbable that E. bifistulosum, together with E. fluitans, Baker, from 
Madagascar, should be united with the Brazilian E. melanocephalum, Kunth; there 
is, however, a slight difference in the structure of the peduncles and in the texture of 
the bracts and sepals. But they require further investigation from a larger series of 
specimens than is at my command before a correct decision can be made. From the 
Indian ZL. setaceum, Linn. (which it closely resembles in general appearance) the 
glabrous petals of ZF. bifistulosum readily distinguish it. The Australian plant 
named E. setaceum by Bentham is quite different in floral structure from all the 
species above mentioned. 
7. BE. submersum, Welw. ex Rendle in Cat. Afr. Pl. Welw. ii. 100, 
not of Tate. Plant submerged in water 2-3 ft. deep, flowering and 
fruiting under water. Leaves very numerous, densely rosulate, 2-4 in. 
long, not exceeding 4 lin. in greatest breadth, linear-filiform, vivid 
green, soon becoming very flaccid when taken out of water. Peduncles 
usually numerous in adult plants, 6-13 in. long, } to rather more than 
3 lin. thick, terete, 5—7-ribbed, glabrous; their sheaths 13-2} in. long, 
oblique at the mouth, often bifid or trifid at the membranous ape%; 
glabrous. Heads. 24-3} lin. in diam., depressed-globose, black, mon®- 
cious, with the male and female flowers mixed. Involucral-bracts 
g—1} lin. long, 3-3 lin. broad, oblong-obovate, obtuse, membranous, 
blackish, glabrous. Flowering-bracts 1-11 lin. long, } to nearly } lin. 
broad, oblanceolate or spathulate-oblanceolate, acute, or the outer 
obtuse, membranous, glabrous, blackish. Receptacle slightly hairy 
(ex Rendle). Female flowers shortly pedicellate. Sepals 3, slightly 
