BOTANICAL GAZETTE. 51 



any one but himself had ever detected this form until he was recently 

 shown unnamed specimens in the herbarium at Cambridge, collected 

 a few years since by Wm. Boott, Esq., of Boston. 



P. LATERALIS. — Stem filiform, branching; floating leaves elliptical, 4- 

 6 lines long and 2 wide, with 5-7 nerves deeply impressed beneath, 

 tapering at the base into a somewhat dilated petiole shorter than the 

 blade; submerged leaves linear, acute, 1-3 inches in length and i^- 

 ^ line wide, 1-3 nerved, the lateral nerves often obscure, the mid- 

 nerve large and often with fine veins or cellular reticulations on each 

 side, biglandular at base as in P. pusil/us, but the glands few 

 and small and often obsolete; stipules free, short, obtuse when young; 

 peduncles with a very peculiar lateral appearance, (as is also the case 

 with the floating leaves,) widely spreading at maturity, sometimes 

 even recurved, ^'2-2 inches long, often thicker than the stem ; spikes 

 commonly interrupted, 2-4 flowered ; fruit obliquely obovate, scarce- 

 ly a line long by ^ of a line broad, the back much curved, obtuse, 

 with two fine grooves upon it, face slightly arched and surmounted by 

 the nearly sessile stigma, the embryo oval in its curve, the apex near- 

 ly touching the base. 



This plant has been rarely found, and specimens of it not fully de- 

 veloped have been referred to P. pusi/lus, with which it is allied, but 

 Mr. C. E. Faxon discovered it the last season at Dedham, Mass., 

 with abundant floating leaves and good fruit which seem to establish 

 its claim to a specific rank. 



P. PUSILLUS, L., var. polyphyllus. — A dwarf form, 3-5 inches 

 high, divaricately branching from the base, and very leafy throughout ; 

 leaves very obtuse, not cuspidate, 3-nerved ; non-flowering but abund- 

 antly provided with propagating buds which are formed on the thick- 

 ened and hardened ends of the branches, and closely invested by im- 

 bricated leaves. 



Sept. —In a shallow pool, with oozy bottom, some distance under 

 water, at South Natick, Mass. 



P. GE.MMIPARUS, Robbius in herb. — Stem filiform, branching, terete, 

 greatly varying in height, rising from i to 4 feet according to the 

 depth of the water in which it grows ; the internodes below, especial- 

 ly in deep water forms, often five inches long; leaves hair like, some 

 times not as broad as the stem, often with no perceptible midrib, 

 plane or canaliculate above, and tapering to the finest point, 1-3 

 inches long, biglandular at base; stipules ^-i inch in length, acute or 

 obtuse, mostly deciduous ; spikes few, interrupted, 3-6 flowered, on 

 long, filiform peduncles ; fruit very rare, and like that of P. pusillus,Qyi 

 cept that it is flatter and somewhat impressed on the sides ; common- 

 ly propagated by gemmiie, which are abundant. The leaves and stems 

 are often alike in size, so that the plant seems to consist of threads, 

 and this, with the long, naked internodes, renders its jtppearance very 

 peculiar. 



P. pusillus, L. , var., gemmipariis, Robbins, in Gray's Man., Ed. 5. 

 The mature fruit of this rare species was obtained at Amherst, 



