Herb floating, smooth, with numerous, long, thread-shaped roots. 
Stems several, procumbent, from 6 to 10 inches or more long, 
simple, or slightly branched, putting out roots from the lower 
joints, bluntly 4-angled, smooth, leafy. Leaves opposite, on short 
petioles, egg-shaped, somewhat tapering at the base and forming 
a slight margin to the petiole, quite entire, smooth, rather succulent, 
bright green, with the mid-rib and margin often red or purplish. 
Flowers in the axils of the leaves, solitary, sessile, small, greenish 
and inconspicuous, each accompanied at its base by two small, 
pointed bracteas. Calyx with 4 triangular segments. Corolla 
wanting. 
Isnardia palustris has very much the habit of Pcplis portula, 
t. 220. ; it is a native of Europe, Siberia, and Persia, where it 
grows in marshes and slow-running water. It was first added to 
the British Flora by W. Borrer, Esq. who found it growing in a 
pool at Buxstead, Sussex, in 1827. Specimens of this very inter- 
esting plant have often been kindly communicated to me by Mr. 
Borrer ; but the specimen from which the drawing for the accom- 
panying plate was made, was sent to me in August last (1841), by 
my kind friend Mr. Edward Jenner, of Lewes, Sussex, a most 
indefatigable Botanist. 
A variety with the leaves more acuminated at both ends, is found 
in North America. 
Sixteen species of Isnardia are described in De Candolle’s 
Prodromus Systematis Naturalis Regni Vegetabilis ; and in Don’s 
General System of Gardening and Botany; most of which are * 
separated from the old genus Ludwegia. 
The Natural Order Onagrari.e, is composed of dicotyledonous 
herbs or shrubs ; with opposite or alternate, simple, entire, or 
toothed leaves ; and red, purple, white, blue, or yellow flowers, 
which are either axillary, or disposed in terminal spikes or racemes. 
The calyx is superior, tubular, with a 4- or 5-lobed limb ; the lobes 
cohering in various degrees, with a valvate a?stivation. The petals 
are generally equal in number to the lobes of the calyx, into the 
throat of which they are inserted, mostly regular, with a twisted 
aestivation, rarely wanting. The stamens are sometimes equal in 
number to the petals, but usually twice that number ; with distinct 
filaments, and oblong or egg-shaped anthers. The ovary is many- 
celled, usually crowned by a cup-shaped gland ; with a thread- 
shaped style, and a capitate or lobed siigma. The fruit is a berry 
or capsule, with from 2 to 4 cells. The seeds are numerous, with- 
out albumen ; and have a straight embryo ; a long and taper radicle; 
and very short cotyledons. 
The British Genera of this order, are Epilobium, t. 14. ; CEno- 
thcra, t. 257.; Circaa, t. 9. ; and Isnardia, t. 4 42. The properties 
of Onagrarice are few, or unknown. (Enotliera biennis, t. 257, is 
sometimes cultivated for the sake of its eatable roots, as a sort of 
salad. 
