HYDROCHARIDACE. 77 
ORDER LXXIX._HYDROCHARIDACEA. 
Aquatic herbs generally perennial, submerged, or with the upper 
leaves floating; the flowers rising out of the water, or at least to 
the surface, at the time of fertilisation. Rootstock with runner-like 
stolons producing a new plant at their extremity, more rarely sobo- 
liferous. Leaf-bearing stem undeveloped or elongated and branched. 
Leaves all radical or opposite or verticillate ; when submerged, pel- 
lucid, simple, undivided; when the lamina is stalked it is often 
cordate at the base; venation generally cancellate. Flowers com- 
monly dicecious, rarely polygamous, enclosed in a spathe of 1 to 3 
bracts while in bud. Male flowers usually several, rarely solitary, 
enclosed in a 1- or 2-leaved spathe: perianth of 6 (rarely 3) segments ; 
the 3 outer generally herbaceous; the 3 inner petaloid, rarely absent: 
stamens inserted at the bottom of the perianth, 3, 6, 9 or many, some 
of them frequently sterile; filaments free or monadelphous; anthers 
introrse, rarely extrorse, 2-celled: ovary rudimentary. Female and 
perfect flowers solitary, from a tubular spathe: perianth with a tube 
united to the ovary; limb 6-partite. rarely 3-partite; the 3 outer 
segments generally herbaceous; the 3 inner petaloid, rarely absent: 
stamens without anthers, or (in the perfect flowers) with anthers 
similar to those of the male flowers: ovary inferior, adnate to the 
tube of the perianth, of 3, 6, or 9 carpels, and generally of as many 
cells as carpels, sometimes 1-celled when there are 3 carpels, and 
in that case with 3 parietal placentae; ovules numerous; placente 
gelatinous, usually on the dissepiments in the multilocular ovaries; 
styles short or sometimes elongated and connate, with the tube of the 
perianth as many as the number of the carpels; stigmas entire or 
2-cleft. Fruit ripening under water, indehiscent, herbaceous. Seeds 
numerous, indefinite; testa membranous, very often clothed with 
spiral fibres; albumen none; radicle pointing towards the hilum or 
away from it. 
GENUS L—HYDROCHARIS. Linn. 
Flowers diccious. Male flowers usually 3 in an umbel, pedicellate 
from a 2-leaved membranous spathe supported on a scape: perianth of 
6 leaves, the 3 outer leaves oval, subherbaceous; the 3 inner larger, 
suborbicular, and petaloid: stamens 12; filaments united at the 
base, forked at the apex, 9 only (or more rarely 6) of them with 
anthers which are attached to the posterior fork of the filament: ovary 
