836 CXLIII. ALISMACEiE. 



bearing an umbel of 3-20 flowers at its apex ; bracts below the umbel 

 scarious, |-f in. long, ovate, acute ; pedicels very variable in length, 

 1-6 in. long in the same umbel. Sepals 3, herbaceous, ^ by | in., 

 elliptic, obtuse, reticulately veined, persistent. Petals white, fugacious, 

 rollicles 6-7, reticulately veined, tapering into short beaks. Seeds very 

 numerous, oblong, with rounded ends, about Jq in. long, dark brown, 

 shining. Fl. B. I. v. 6, p. 562 ; Dalz. & Gibs. p. 249 ; Micbeli, in DC. 

 Monog. V. 3 (1881) p. 87 ; Woodr. in Journ. Bomb. Nat. v. 13 (1901) 

 p. 429 ; Prain, Beng. PI. p. 1120. Butonms lanceolatus, Eoxb. Hort. 

 Beng. (1814) p. 89; Grab. Cat. p. 251.— Flowers : Nov. 



Rare in the Bombay Presidency. Gujarat : tank at Chikli near Surat, Law ex 

 Graham ; Godra, Woodrow. — Distrib. Plains of India ; Tropics of the Old World, 

 Australia. 



Ordee CXLTV. NAIADACEJE. 



Aquatic or marsh herbs of various habit ; rootstock stout or slender, 

 sometimes tuberous, often creeping or ; stem floating or rooted in 

 the ground. Leaves entire or serrate, submerged or floating, sheathing 

 at the base, sometimes stipulate. Flowers 1- or 2-sexual, green, usually 

 inconspicuous, in spikes, racemes, or terminal or axillary pedunculate 

 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 flowers, 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 ; stigma usually simple, sometimes 

 stigmas 2-3 capillary. Fruit various. Seeds erect, pendulous, or 

 laterally peltate ; testa coriaceous or somewhat fleshy ; albumen ; 

 embryo fl^eshy, straight. — Distrib. Genera 16 ; species about 150, 

 temperate and tropical. 



Flowers 2-sexual. 



Perianth of sepals present ; carpels sessile. 



Sepals 1-3, white, pink or pale blue, membranous ; 



stamens 6 or moi-e 1. Aponogeton. 



Sepals 4, green, herbaceous ; antliers 4, sessile 2. Potamogbton. 



Perianth wanting ; carpels stipitate ; anthers 2, sessile ... 3. Rdppia. 

 Flowers 1 -sexual. 



Style long, slender ; stigma oblique, peltate ; achencs 2-9 ; 



male perianth wanting 4. ZanniciielliA. 



Style wanting; stigmas 2-4, slender; achene solitary; 



male perianth double 5. Naias. 



1. APONOGETON, Linn. f. 



Scapigerous fresh water herbs ; rootstock tuberous, crowned by 

 numerous root-fibres. Leaves oblong, floating or submerged, mem- 

 branous. Flowers 2-sexual, on long scapes bearing solitary or 

 geminate, often unilateral spikes, which when young are enclosed 

 in a conical quickly deciduous sheath. Perianth of 1-3 equal or 

 unequal pink, \\hite, or pale blue segments or obsolete. Stamens 6 or 

 more ; filaments subulate, unequal, persistent ; anthers didymous. 

 Carpels 3-6 ; ovules 2 or more in each carpel, basal, auatropous ; style 

 short or ; stigma discoid or decurrent, persistent. Seeds erect ; testa 

 thick or thin ; albumen ; embryo straight. — Distrib. Species 22, 

 Asiatic, African, and Australian. 



