1146 ZANNICHELLIA. [CLASS XXI. ORDER I. 
4 
species, it will be seen how much larger the cells are in one species~ 
than another. The C. verna, the most common of the genus, grows 
in great abundance in most pools and slow streams, and though by 
no means an attractive plant from its external beauty, is, never- 
theless, of great utility in purifying the water, and affording covering 
and food to fish and numberless insects. 
“Tf the thing we seek 
Be genuine knowledge, bear we then in mind 
How, from the lofty throne, the sun can fling 
Colours as bright on exhalations bred 
By weedy pools or pestilential swamp, 
As by the rivulet sparkling where it runs, 
Or the pellucid lake.” 
GENUS III. ZANNICHEL’LIA—Lixn. Horned Pondweed. 
Nat. Ord. Potam'ra. Juss. 
Gen. Cuar. Flowers solitary, barren flower a single naked stamen, 
inserted at the outside of the base of the perianth of the fertile 
flower, which is campanulate, surrounding two to six ovaries. 
Stigma peltate. Fruit dry, single seeded, compressed, gibbous, 
crenated externally—Named in honour of John Jerome Zanni- 
chelli, a Venetian apothecary and botanist. 
1. Z. palus'tris, Linn. (Fig. 1378) Common Horned Pondweed. 
Anthers of four cells ; style long; stigma entire. 
English Botany, t. 1844.—English Flora, vol. iv. p. 70.—Hooker, 
British Flora, ed. 4. vol. i. p. 329.—Lindley, Synopsis, p. 251. 
fioot long slender fibres. Stem long, slender, thread-shaped, much 
branched and leafy, floating. Leaves opposite, linear, very narrow, 
entire, acute, or sometimes emarginate at the point. lowers axil- 
lary, enveloped in a membranous bractea, containing the barren 
flower, a single stamen, with a long white filament, and an oblong 
four celled anther, fertile flower on a short stalk, its perianth bell- 
shaped, cloven, containing four or five oblong compressed ovaries, 
each on a short footstalk, somewhat keeled and toothed at the back. 
Style half as long, or as long as the fruit. Stigma peltate. Capsules 
oblong, incurved, somewhat compressed, one celled, one valved, single 
seeded, 
Habitat.—Pools, ditches, and stagnant water. 
Annual; flowering in August. 
This, like most other water plants, is very variable, in its different 
parts being elongated or contracted by the increase or dimmution of 
the water; when the stems are much elongated, it is the Z. major, 
Reichenbach; when grown in shallow water, with the roots creeping, 
