CX. NAIADACEiE 
547 
Leaves ovate, oblong or lanceolate. 
Leaves entire. 
Leaves stalked. 
Leaves 4-5 in. long 1. P. natans. 
Leaves ^-1 in. long ....... 2. P.javanicus. 
Leaves stem-clasping . . . . . . . 8 . P. perfoliatus. 
Leaves finely toothed. 
Flower- spikes ^ in. long 4. P. crispus. 
Flower-spikes 1^-2 in. long . . . . . . 5. P. lucens. 
Leaves very narrow, grass-like . . . . . . 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, Hassk. ; FI. Br. Ind. vi. 566. Stems 
very slender. Leaves alternate or the upper ones opposite, 
stalked, ovate-oblong, J-1J 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 £ 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, 
N N 2 
