176 FLORA 
Potamogeton. 
Leaves dissimilar; floating leaves firm, on long stalks; 
submerged leaves membranous alternate. 
_ Floating leaves 2 to 4 in., oval, subcordate, about 
20-nerved ; fruit ovoid, 3-angled on the back, 
shortly beaked see a +P a ¥ 
Floating leaves elliptical or lanceolate, about 1 in., 
few-nerved; fruit distinctly beaked 
Leaves all submerged, flat, membranous, simply sessile. 
Leaves undulate-crisped on the margin, narrow- 
oblong, blunt, with a strong central nerve and 
one on each side of it ae te Me 
Leaves narrow-linear, obtuse, l-nerved; stipules 
blunt; flower-spikes about 4 in. long, of several 
flowers Ka ee ne oF cit. ty 
Leaves narrow-linear, acute, 1- or 3-nerved ; stipules 
acute; spikes short, few-flowered vel 
Leaves all submerged, mostly dilated and clasping at 
the base. Stems filiform, dichotomously branch- 
ing; leaves narrow-linear, alternate... 
Posidonia. 
Stems branched; leaves very long, broad-linear, rounded 
at the end ore 
Ruppia. 
Stems and branches very slender; leaves capillary, 
long, clasping " pe bee 
Zostera. 
Each flower subtended by a transverse vertical bract, 
flowers few; leaves narrow-linear, truncate or 
notched at the end, up to 1 or 2 feet long, the 
sheathing base rather short ii Si 
Flowers several, without bracts ; leaves rounded at the 
at the end, sheathing base about one inch long 
Lepilaena. 
Stems filiform, much-branched ; styles longer than the 
carpels; flower-stalks very short; calyx-lobes 
rather longer than the carpels oe bie us 
Styles much shorter than the carpels; flower-stalks 
lengthening to about 4 inch; calyx-lobes ovate, 
very short : 
Cymodocea. 
Stems and branches hard; leaves firm, broad-linear, 
truncate or toothed at the end, 1 to 3 inches long 
OF SOUTH AUSTRALIA. 
Tepperi 
tenuicaulis 
crispus 
ochreatus 
acutifolius: 
pectinatus. 
australis 
maritima 
nana 
Tasmanica 
Preissii 
australis 
antarctica 
