THE TASMANIAN FLOBA. 



227 



Leaves broad, stalked 



1. P. natanx. 



2. /'. perfolifitus. 



3. P. prmlonffus. 



4. P. dbtunfolius. 

 6. P. pectinatun. 



Leaves opposite, connate 



Leaves sessile, ovate, upper ones opposite 



Leaves linear, obtuse 



Leaves filiform, acute ... 



1. P. NATANS, Linn. Leaves broad, ovate or oblong, on long stalks, tbe lower 

 ones submerged, narrower, and usually crisped on the margin ; upper ones thick, 

 floating, 1-2 inches long or rarely longer. Flowers in a dense cylindrical spike, 

 about 1 inch long, on a rather short robust stalk. P. heterophyllus, Hook. " Fl. 

 Tas." (included). 



Common in fresh water ; also throughout Australia and most temperate and 

 sub-tropical parts. Fl. N"ov.-Dec. 



The Tasmanian forms often somewhat approach P. heterophyllus, Schreb. 

 P. cheesmanii, Bennett, is also referable here. 



2. P. PEEFOLIATUS, Linn. Stems usually very long, with numerous submerged 

 leaves in opposite pairs, often connate, the upper ones only alternate, broadly 

 ovate, about 1 inch long. Flowers in small, rather dense, spikes, ^-f inch long, 

 on lateral and terminal peduncles. 



South Esk River. It occurs also in New South Wales, Victoria, and 

 Queensland. Common in the Northern Hemisphere. Fl. Nov. -Dec. 



.3. P. PEajLONGUS, Wulf. Stems elongated. Leaves submerged, alternate, 

 sessile, narrow-oblong, stem-clasping, the upper ones only opposite, 2-4 inches 

 long. Flowers in a short dense spike, J-1 inch long, on a rather short, thick, 

 terminal stalk. 



South Esk River (probably in error) ; also in Victoria. Common in the 

 Northern Hemisphere. Fl. Nov.-Dec. 



Doubtfully identical with P. prtelongus, Linn. Mueller considers it a 

 form of P. polygonifoliw. Pour., but that species has long petioles. 



4. P. OBTUSiPOiiius, Mert. et Koch. Stems slender, rather spreading. Leaves 

 all submerged and alternate, except the upper ones, thin, linear, .3-nerved., 

 obtuse, but not conspicuously so, mostly 1^ inch long. Flowers few, in a small 

 spike, on terminal and lateral stalks. P. graminem, Hook. " Fl. Tas. ;" P. 

 pusillus, Linn. 



Jordan River, near Campbell Town, South Esk River. It occurs in New South 

 Wales, Victoria, South Australia, and West Australia. Common in the Northern 

 Hemisphere. Fl. Oct.-Nov. 



5. P. PECXINATUS, lAnn. Stems very slender and often much elongated. 

 Leaves very slender, alternate, 2 or 3 inches long, the base usually distinctly 

 sheathing, 1-nerved Flowers in terminal or lateral interrupted spikes, on short 

 or long stalks. P. marinun, Linn. 



Bridgewaler marshes ; also in Victoria and South Australia. Common in the 

 Northern Hemisphere. Fl. Oct.-Dec. 



3. RUPPIA. 



Flowers hermaphrodite. Perianth none. Stamens of two 2-celled sessile 

 anthers. Pistil of 4 distinct sessile carpels, each bearing a single ovule. Fruit 

 four 1-seeded nuts, each raised on a stalk. 



The genus contains but one species, but has a distribution throughout 

 temperate and sub-tropical regions of the globe. 



R. MAEixiMA, Linn. Stems slender, elongated, and much-branched. Leaves 

 all submerged, filiform, mostly alternate, 2 to many inches long, sheathing at the 

 base. Flowers two together or solitary, on a long filiform peduncle formed 

 and coiled in the axil of a leaf ; when the fliower is mature the peduncle uncoils 



