64 ENGLISH BOTANY. 
British Potamogetons in the Kew Herbarium, I did not perceive any 
plant to which this name was applicable. 
It may be known by its having the large fruit of P. natans, and the 
leaves similar to those of the deep water forms of P. polygonifolius, 
The nearest approach we have to it is the plant called P. sparganiifo- 
lius by Professor Babington; but that has always a branched stem, 
while P. fluitans has a simple one, like that of P. natans. 
P. GRACILIS. Fries. 
At one time Professor Babington was inclined to believe that a 
plant gathered by Professor Olliver, near Dunstanburg, Northumber- 
land, might prove to be this species; but in the fifth and sixth editions 
of the ‘ Manual” he says it seems to be P. pusillus. 
ORDER LXXVUI—ALISMACE &. 
Marsh or aquatic perennial herbs, or very rarely annuals, with a 
creeping or cormose rootstock. Leaf-bearing stem generally unde- 
veloped. Leaves commonly all radical, sheathing at the base, simple, 
linear, or with an enlarged lamina which is sometimes cordate or 
sagittate at the base and with parallel or cancellate venation. Stipules 
none or nearly wholly adnate. Flowers perfect (rarely unisexual and 
moneecious) on a leafless radical scape, arranged in a panicle, raceme, 
or umbel—rarely in a raceme at the extremity of a leafy stem. 
Perianth regular, of 4 or 6 leaves; in the latter case the 3 outer ones 
often smaller and herbaceous, the 3 inner larger and petaloid, some- 
times all the 6 petaloid, occasionally all the 6 subherbaceous. Stamens 
6 to 9, or numerous. Ovary superior, free from the calyx, of 3, 6, or 
numerous carpels, which are either distinct from the first or separate 
into cocca or follicles when the fruit is ripe, rarely the carpels are 
reduced to one; ovules 1 or 2 (rarely more) in each carpel; styles 
commonly short or almost absent; stigmas simple, more rarely plumose. 
Fruit of dry carpels or cocca. Seeds solitary, 2 or rarely many in 
each carpel, with a coriaceous testa, destitute of albumen; radicle 
pointing towards the hilum. 
Suzs-Orper I.—JUNCAGINACEE. 
Perianth with the segments all similar, herbaceous or somewhat 
coloured. Stamens 6 or 7; anthers extrorse. Seeds 1 or 2 in each 
cell of the ovary; embryo straight. 
