312 _' NAIADACEA. [ AponoGETON, 
. 
base. Flowers 1-or 2-sexual, usually green and inconspicuous, in 
spikes, racemes or terminal or axillary peduncled spadices; bracts 
small or 0. Perianth 0 or of 3-4 inferior, valvate segments or 
tubular and very delicate. Stamens 1-6, hypogynous, free in 
2-sexual, solitary or connate in male flowers; anthers 1-2-celled. 
Carpels 1-6; ovules 1 or more in each carpel, erect or pendulous ; 
style long or short; stigmas 2-3 capillary or more often simple. 
Fruit of utricles, achenes, follicles or small drupes. Seed erect, 
pendulous or laterally peltate, testa coriaceous or somewhat fleshy, 
albumen 0, embryo fleshy, straight. Species about 150, tem- 
perate and tropical. 
Flowers 2-sexual, perianth of 1-4 sepals. 
Sepals 1-3, white or coloured ; stamens 6 or . 
more . E ; : ; : . 1. APONOGETON. 
Sepals 4, green ; anthers 4, sessile. . 2. POTAMOGETON. 
Flowers l-sexual, perianth 0 or hyaline. 
Style long with Renee, bg pHEmA, 
achenes 2-9 . . 3, ZANNICHELLIA. 
Style 0, stigmas 2-4, at seiere : . 4. Natas. 
1. APONOGETON, Thunb.; Fl. Brit. Ind. vi, 564. 
Scapigerous, aquatic herbs, rootstock tuberous crowned by 
numerous root fibres. Leaves oblong or linear-lanceolate, floating 
or submerged. Flowers bisexual on long scapes bearing solitary 
or geminate often unilateral spikes which when young are enclosed 
in a conical fugacious sheath. Perianth of 1-3 equal or unequal 
white or coloured segments or obsolete. Stamens 6 or more; 
filaments subulate, unequal, persistent; anthers didymous, 
Carpels 3-6, each 2 or more ovuled; style short or 0; stigma 
discoid or decurrent, persistent; ovules basal, anatropous. Fruit 
of coriaceous follicles. Seeds oblong or cylindric, sometimes 
ribbed. Species about 22, Africa, Madagascar, tropical Asia and 
Australia. 
Leaves floating, spikes <a carpels 4-8- 
seeded . ° P ; : . 1. A. monostachyon., 
Leaves are submerged, spikes not dense, 
carpels 1-2-seeded . : : . 2, A. erispum, 
