FLORA OF TROPICAL AFRICA. 



Order CXLI. PONTEDERIACE^. (By N. E. Brown.) 



Flowers hermaphrodite, all alike or some cleistogamous, regular or 

 slightly irregular. Perianth inferior, petaloid ; segments C, 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 difierent 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 

 fascicled along the axis of the spike, or rarely with a solitary and axillary 

 flower. 



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 . . . .1. Heteeantheba. 

 Stamens 6 in the expanded flowers : 



Perianth segments united into a tube below . . 2. Eichornia. 



Perianth segments free to the base . . . .3. Momochoria. 



Excluded. 



SCHCENLANDIA GABONENSis, Comu in Bull. Soc. Bot. France, 1896^ xliii. 21, is 

 Cyanastrum cordlfollum, Oliv. in H^EMODORACEiE. 



