CX. NAIADACEJE 
547 
Leaves ovate, oblong or lanceolate. 
Leaves entire. 
Leaves stalked. 
Leaves 4-5 in. long 
Leaves |-1 in. long 
Leaves stem- clasping 
Leaves finely toothed. 
Flower-spikes ^ in. long . 
Flower-spikes l|-2 in. long 
Leaves very narrow, grass-like. 
1. P. natans. 
2. P. javanicus. 
3. P. perfoliatus. 
4. P. crispus. 
5. P. lucens. 
6. P. pectinatus. 
* 1. Potamogeton natans, Linn. ; FI. Br. Ind. vi. 565. Leaves 
alternate or the upper ones opposite, stalked, ovate-oblong, 2-6 
in., pointed at both ends, entire. Spike 1-2 in. ; flowers crowded. 
Plains of the Punjab, ascending to 5000 ft. ; May-October. — Most temperate 
climates, including Britain. 
2. Potamogeton javanicus, Hassle . ; FI. Br. Ind. vi. 566. Stems 
very slender. Leaves alternate or the upper ones opposite, 
stalked, ovate-oblong, f-lj in., pointed at both ends, entire. 
Spike in., interrupted ; flowers very small. (Fig. 179.) 
Simla ; May-October. — Plains of India, ascending to 7000 ft. — Tropical 
Asia, Africa and Australia. 
* 3. Potamogeton perfoliatus, Linn. ; FI. Br. Ind. vi. 566. 
Stems robust. Leaves alternate or the 'upper ones opposite, 
broadly ovate, 1-4 in., entire, stem- clasping. Spike f in. ; flowers 
crowded. 
Kashmir-Kumaon, 4000-8000 ft. ; May-October. — N. temperate regions, 
including Britain, Australia. 
*4. Potamogeton crispus, Linn. ; FI. Br. Ind. vi. 566. Stems 
slender. Leaves alternate and sessile or the upper ones opposite 
and stem-clasping, linear-oblong, 1-3 in., margins very wavy, 
