CLASS XXI. ORDER VII. | CERATOPHYLLUM. 1201 
This curious little plant grows in crowded tufts, and frequently be- 
comes detached from its long roots, forming small floating islands. 
The description above given of the flowers is that of Sir W. J. 
Hooker, who has paid particular attention to this remarkably curious 
genus of plants. The leaves and scape are extremely beautiful when 
seen by a magnifying power, and is a beautiful example of the muri- 
cated cellular structure. 
ORDER VII. 
POLYAN'DRIA. Many SramMens. 
GENUS XVII. CERATOPHYL’LUM.—Linn. Horn-wort. 
Nat. Ord. CERATOPHYL'/LER. GREY. 
Guy. Cuan. Barren flowers with an inferior many partite perianth. 
Stamens sixteen to twenty. Lertile flowers with a many partite 
perianth. Ovariwm superior. Style filiform, curved, simple. 
Fruit a one celled nut, with a pendulous seed—Name from 
xeeas xfeatos, a horn; and $varoy, a leaf; in allusion to the 
forked leaves. 
2. C. demer'sum, Linn. (Fig. 1458.) Common Horn-wort. Leaves 
whorled, with bristle-shaped segments; fruit armed with two spines 
near the base, and terminated by the curved subulate style. 
English Botany, t. 947.—-English Flora, vol. iv. p. 141.—Hooker, 
British Flora, ed. 4. vol. i. p. 347.—Lindley, Synopsis, p. 225. 
Root fibrous, the whole plant a dark green, growing entirely under 
water. Leaves about eight in a whorl, densely crowded, cut into 
dichotomous slender awl-shaped segments, more or less toothed on 
the margin. Flowers all axillary, sessile, with a thin white erect 
membranous perianth, more or less deeply cut into segments. 
Stamens with erect oblong spotted two celled anthers, about twenty. 
Fruit ovate, green, armed towards the base on each side with a pro- 
jecting horn, of greater or less length, and crowned with the curved 
slender awl-shaped stile. 
Habitat.—Slow running streams and ditches; frequent. 
Perennial ; flowering in July. 
2. C. submer'sum, Linn. (Fig. 1459.) Spiked Water Milfoil. 
eaves whorled, with bristle-shaped segments ; fruit without spines at 
the base, and terminated by the short mucronate style. 
English Botany, t. 679.—English Flora, vol. iv. p 142.—Hooker, 
British Flora, ed. 4. vol. i. p. 347.—Lindley, Synopsis, p. 225. 
This is very similar to the last species. The leaves are, perhaps, in 
more distant whorls, with entire scarcely even toothed segments, and 
