140 CL, AROIDEZ (BROWN). [ Pistia. 
1. PISTIA, Linn.; Benth. et Hook. f. Gen. Pl. iii. 964. 
Spathe small, tubular below; limb open, oblique, constricted on 
each side at its base. Spadix shorter than the spathe, monecious ;. 
female part adnate to the back of the spathe ; male part free, stipitate, 
having two neuter organs at its base, the upper cup-shaped or frill-like, 
the lower suborbicular or subreniform in outline, with the sides bent 
inwards or downwards. Flowers unisexual. Perianth none. Female 
inflorescence of a single ovary, apparently arising from the back of the 
spathe, very oblique, 1-celled ; style obliquely erect from the top of the 
ovary ; stigma capitate ; ovules numerous, basal, orthotropous. Male 
inflorescence of a stipitate whorl of 3-8 flowers; each flower composed 
of 2 connate 2-celled anthers, opening by short slits. Fruit ellipsoid, 
with a thin pericarp, many-seeded. Seeds cylindric-oblong, truncate at 
each end, depressed at the apex, with an operculum closing the micro- 
pyle, rugulose ; testa thick, composed of a brown membranous outer 
and inner skin, and a thick white cellular layer between them ; embryo: 
minute, apical.—A floating, stoloniferous, stemless herb, with a tuft of 
fibrous roots. Leaves in a rosette; veins flabellate, raised beneath. 
Spathes axillary, with very short peduncles. 
A genus of one species, very variable in the form of its leaves, found throughout 
the tropical and sub-tropical regions of the globe, in still, fresh water. 
1, P. Stratiotes, Linn. Sp. Pl. ed. 1,963. Leaves sessile in a 
rosette, 1—5 in. long, 1-2 in. broad, cuneate-oblong cr cuneate-obovate,. 
Berlin, 1853, 354 (reprint 26). 
Upper Guinea. Senegal, Lelievre, Heudelot (ex Engler). Ashanti: Assin- 
Yan-Coomassie, Cummins! Niger Territory : Nupe; Lom, Barter, 176! River 
