548 
CX. NAIADACEiE 
having the appearance of being lobed, finely toothed. Spike J in. ; 
flowers from 3-6. 
Kashmir- Bhootan, 4000-6000 ft. ; May-October. — Plains of India. — N. and 
S. tropical and temperate regions, including Britain. 
* 5. Potamogeton lucens, Linn. ; FI. Br. Ind. vi. 567. Stems 
robust. Leaves alternate or the upper ones opposite, lanceolate, 
4-10 in., sessile, margins very slightly wavy, finely toothed. 
Spike l|-2 in., thick ; flowers crowded. 
Kashmir-Kumaon, 5000-7000 ft. ; May-October. — N. temperate regions, 
including Britain, Australia. 
* 6. Potamogeton pectinatus, Linn. ; FI. Br. Ind. vi. 567. 
Stems thread-like, much-branched. Leaves alternate, very 
narrow, grass-like, 3-8 in., base sheathing ; stipules appearing as 
very small lobes on the margin of the leaf -sheath. Flowers in 
small, separate clusters forming an interrupted spike. 
Common in the plains, ascending to 12,000 ft. ; May-October. — Spread over 
most regions, including Britain. 
2. ZANNICHELLIA. In honour of Zannichelli, a Venetian 
botanist. ‘ — Temperate and tropical regions. 
*Zannichellia palustris, Linn. ; FI. Br. Ind. vi. 568. A very 
slender, submerged plant ; stems 3-6 in., branched. Leaves linear, 
1-3 in., opposite or in threes ; stipules small, sheathing, mem- 
branous. Flowers minute, 1 -sexual, a male and a female sessile 
in the leaf -axils within the stipules. Perianth none. Male flower : 
a single stamen, filament long, anther 2-celled. Female flower : 
ovary of 4 distinct carpels each 1 -celled and 1-ovuled, style long, 
stigma terminal, disk-shaped. Achenes 2-4, curved, flattened, 
usually wrinkled or tubercled, sometimes shortly stalked, tipped 
by the withered style. 
Common in marshes and ponds throughout India, ascending to 15,000 ft. ; 
May-October. — Spread over nearly all regions (Britain, Horned Pondweed). 
3. NAIAS. From • the Greek naias, a water nymph. — Tem- 
perate and tropical regions. 
*Naias major, Allioni ; FI. Br. Ind. vi. 569. A slender, sub- 
merged herb ; stems often long-branched and interlacing, rough 
with short outgrowths. Leaves opposite or whorled, linear, J-1J 
in., deeply and sharply toothed, base sheathing. Flowers minute, 
axillary, sessile, 1-sexual, the male and female on different plants. 
Male flowers : perianth tubular, 2-3-toothed ; anther 1, sessile, 4- 
celled, enclosed in and adnate to the perianth. Female flowers : 
