99 



.' 1W. P. poliosus, Raf. 



l\ pauciflorus, Pursh. 



Billings Bridge. (/. Macoun.*) Rideau Canal. Stem filiform, 

 much branched. Leaves 1 2 inches long, narrowly linear, acute, 

 obscurely 3-nerved, not glandular at base. Spikes capitate 1 4 

 flowered on short erect club-shaped peduncles; fruit roundish- 

 lenticular, the back more or less crested. 

 2445. P. pusillus, L. 



Stem slender ; leaves narrow, 1 3 nerved with translucent glands 

 on each side at the base. Spikes 2 8 flowered on rather long 

 peduncles, fruit obliquely elliptical, scarcely keeled, apex of em- 

 bryo incurved and directed obliquely downwards. Very variable. 



var. panormitanus, Biv. 



llideau Canal, very local. The most conspicuous difference from 

 the type is the presence of spatulate floating leaves. Rev. Thomas 

 Morong writes as follows of some 'specimens submitted to him : 

 " I have carefully compared these with plants sent me from Sicily 

 as P. pusillus, L var. panormitcmus, Biv., and can see no essential 

 difference. In my specimens the submerged leaves are shorter, 

 they are not ruddy at all, and none revolute. The description of 

 the variety, however, corresponds : leaves longer (than the type), 

 flaccid, the upper flowering ones opposite and spatulate. the whole 

 surface of the leaf with a pretty chain-like areolation. I am sure 

 that your plant meets this description, and when compared as to 

 the floating leaves, the specimens agree. I should not, however, 

 regard it as a distinct species, since it bears so many characters 

 of pusillus. The ruddy tinge and revolute leaves may be owing 

 to the season or accidental circumstances." 



I'll!',. P. major. (Fries) Moron-. 



/'. muoronatus, Schrader, and /'. pusillus, var major, Fries. 

 Not uncommon. Stem much less branching than P. pusillus, and 

 more flattened, the leaves broader, often 5-nerved, and the flower- 

 ing spikes interrupted. 

 2 I 19. P. I'KCTINATUS, L. 



Stems filiform, repeatedly branehed so as to form brush-like mats in 

 shallow water. Spikes interrupted, on long filiform peduncles 



