Naiadece. 371 



Rootstock short, stout, with numerous long stout simple 

 root-fibres; 1. all radical, 6-12 by 4-8 in., sometimes as broad 

 as long, reniformly or deltoidly sagittate or triangular, 

 glabrous or puberulous on both surfaces, basal lobes long, 

 tapering, spreading, as long as the rest of the blade, acute or 

 obtuse or tip rounded, sinus very broad, open, primary veins 

 11-13 pairs, radiating from the top of the petiole, secondary 

 remote, with irregular reticulation between them, petiole 

 2-3 ft., very stout, striate, channelled above; panicle with the 

 stout angular ped., 2-4 ft. long, erect or declinate, branches 

 long, erecto-patent, the lower 4-nately whorled, bracts 

 whorled, broadly ovate-lanceolate, acuminate, lower an inch 

 long, veins parallel; fl. 4-15 in a whorl, J-| in. across, upper 

 mostly male, shortly stoutly pedicelled ; pedicel of fem. and 

 bisexual fl. 1-3 in., very stout; sep. orbicular-ovate, concave, 

 ribbed, green ; pet. broadly obovoid, ^ in. long and broad ; fil. 

 flattened, base dilated, glandular-pubescent; ov. in bisexual fl. 

 15-20, in concentric whorls ; achenes in a globose head |-| in. 

 diam., obovoid, turgid, endocarp dorsally 3-ribbed. 



Tanks and still waters, chiefly in the dry region ; rather common. 

 Fl. Feb., Sept.; white. 



Also in India, Trop. Africa, and Madagascar. 



CXLVL— NAIADES. 



Aquatic herbs, of fresh or salt water, very various in habit; 

 rootstock stout or slender, sometimes tuberous, often creeping 

 or o; stem floating or rooted in the ground; 1. entire or 

 serrate, submerged or floating, often stipulate ; fl. uni- or bi- 

 sexual, often minute or inconspicuous, axillary or spicate, 

 naked, or enclosed in a sheath or spathe; perianth o, or 

 tubular, or of inferior, valvate segments; stam. hypogynous, 

 anth. i-2-celled; ov. of 1-4, i-ovuled, free carpels, style and 

 stigma various, ovule erect or pendulous; fr. various; seed 

 without endosperm, embryo macropodous, straight or curved. 



vStigma disciform or decurrent on the ovary. 

 Perianth of sep. 



Sep. 1-3, white i. Aponogeton. 



Sep. 4, herbaceous 2. Potamogeton. 



Perianth o 3. Ruppia. 



Stigma or stigmas subulate or capillary. 



Fresh- or brackish-water plants . . . .4. Naias. 

 Salt-water plants 5. Cymodocea. 



