FLORA OF TROPICAL AFRICA. 
OrvER CXLI. PONTEDERIACES. (By N. E. Brown.) 
Flowers hermaphrodite, all alike or some cleistogamous, regular or 
slightly irregular. Perianth inferior, petaloid; segments 6, biseriate, 
united into a tube in the lower part, rarely free, equal or the outer 
series smaller. Stamens 3 or 6, rarely 1, usually of two sizes and often 
of different colours; filaments free; anthers basifixed or dorsifixed, . 
2-celled, introrse, opening by longitudinal slits or rarely by terminal 
pores. Ovary superior, 3-celled with axile placentas, or 1-celled with 
3 parietal or more or less prominent placentas; style filiform; stigma 
entire, thickened or subcapitate or shortly 3-lobed; ovules numerous 
and biseriate in each cell or rarely solitary, anatropous. Fruit a many- 
seeded capsule or rarely a 1-seeded achene. Seeds small, ovoid, ribbed ; 
embryo cylindrical, straight, embedded in the centre of a copious 
albumen.—Aquatic or marsh herbs, with the lower part of the stem or 
rhizome often creeping and rooting in the mud, or entirely floating. 
Leaves alternate, hastate, cordate, orbicular, ovate, lanceolate or linear, 
entire, with a sheathing petiole or stipulate, the submersed leaves some- 
times without blades, or different in form. Inflorescence terminal— 
often apparently arising from the petioles of the leaves, the lower part 
of such leaf-stalks being really sympodial branches—either fascicled in 
the sheath of the flowering leaf, or spicate with the flowers solitary or 
ppt along the axis of the spike, or rarely with a solitary and axillary 
ower. 
A small order of about 25 species, chiefly natives of. Tropical Africa and Tropical 
America, about 4 occurring in North America, 2 or 3 in Tropical and Temperate 
Asia, 1 in South Africa, and 1 in Australia, 
Stamens 3 in the expanded flowers . ° . 
Stamens 6 in the expanded flowers: 
Perianth segments united into a tube below 
Perianth segments free to the base . . 
Excluded. 
ScH@NLANDIA GABONENSIs, Cornu in Bull. Soc. Bot. France, 1896, xliii. 21, is 
Cyanastrum cordifolium, Oliv. in HZMODORACE#. 
VOL. VIII. 
1. HETERANTHERA, 
2. EICHORNIA. 
3. MonooHoRIA. 
B 
