variable both in shape and size; simple, entire, minutely dotted; 
the uppermost ones crowded, stalked, elliptic, or inversely egg- 
shaped, 3-nerved above the base, spreading in a star-like form at 
the summit of each branch, and floating on the surface of the water ; 
lower ones distant, spatulate, sometimes strap-shaped and single- 
ribbed. Flowers axillary, solitary, sessile, usually separated, mi- 
nute, and inconspicuous ; staminiferous ones consisting of a single 
stamen, with a yellow anther, on a slender white filament ; and 
2 minute petals or bracteas, which are thick, flat, and bowed in- 
wards at the edge like a crescent (see fig. 1.); pistilliferous ones of 
2 similar petals or bracteas ; 2 hair-like, reflexed styles; and a 
roundish, 4-lobed, 4-celled capsule. 
Dr. Macreight, in his very excellent and useful little book, 
the “ Manual of British Botany,” has described five varieties of 
this species ; viz. 
" a. vulgaris. (D. C.) All the leaves elongato-obovate. C.verna (FI. Dan.) 
** 0. intermedia. (D. C.) Lower leaves linear, obtuse or emarginate ; the 
upper ones oval. C. dubia. (Thuillier.) 
“ y. stellata. (Hop.) All the leaves oval. Stemsshort. C. aestivalis. { Tiiuit.) 
“ 5. ceespitosa. (Schult.) All the leaves oval, rigid, and small. Stem short, 
stellato-patent. In moist scarcely inundated places. 
“ e. tenuifolia. (Pehs.) All the leaves linear ; upper ones 3-nerved.” 
The 2 crescent-shaped petals or bracteas (figs. 1 & 3) ; and the sessile, regu- 
larly 4-angled, bluntly keeled fruit; will distinguish this, in all its varieties, 
from the two other British species. 
“ These plants,” says Professor Burnett, “ do not possess any 
notable properties ; they are innoxious, and perhaps slightly nu- 
tritious, as they are fed on by wild-ducks ; and, growing abundantly 
in damp places, are said, by the large quantities of carbonic acid 
and carburetted hydrogen they absorb, to tend much towards puri- 
fying the air of marshes, and rendering that in water respirable by 
fish and other aquatic animals.” 
The essential character of the Natural Order Callitrichine/e, 
of which the present genus is the only knovvn example, is thus 
given by Professor Lindley. 
“ Flowers usually unisexual, monoecious, naked, with 2 fistular 
coloured bracteae. Stamen single ; filament filiforme, furrowed 
along the middle; anther reniform, I -celled, 2-valved ; the valves 
opening fore and aft. Ovarium solitary, 4-cornered, 4-celled ; 
ovules solitary, peltate ; styles 2, right and left, subulate ; stigmas 
simple points. Fruit 4-celled, 4-seeded, indehiscent. Seeds pel- 
tate ; embryo inverted in the axis of fleshy albumen; radical very 
long, curved, superior ; cotyledons very short. Small aquatic 
herbaceous plants, with opposite, simple, entire leaves. Flowers 
axillary, solitary, very minute.” 
Dr. Lindley remarks, “ the affinity of this order to other Dicotyledones 
appears to be of precisely the same nature as that borne by Lenina to Monocoty- 
ledones. They each exhibit the lowest degree of organization known in their 
respective classes.” 
This very distinguished Botanist fully assents to Dr. Brown’s opinion of its 
affinity with Haloragece, (see folio 376, a.) although he does not place it in the 
same order. See Introd. to Nat. Syst. of Jiot. p. 176. 
