100 MIDDLESEX FLORA. 



P. hybridus, Michx. 

 Winchester ; Silver Lake, Wilmington ; and Round Pond, Woburn 

 (Wm. Boott),; Bedford (Dr. C. W. Swan); Medford, clay-pits (F. 

 S. Collins). 



P. lonchites, Tuck. 

 Winchester (Rev. Thos. Morong) . 



P. pulcher. Tuck. 

 Spot Pond, Stoneham, and Ashland (Rev. Thos. Morong) ; Fresh 

 Pond, Cambridge (E. Tuckerman) ; Concord (Walter Deane). 



P. amplifolius. Tuck. 



Mystic Pond, Medford (Wm. Boott) ; Fresh Pond, Cambridge 



(Rev. Thos. Morong) ; Concord (Walter Deane) ; Tovensend and 



Bedford (Dr. C. W. Swan). 

 P. gramineus, L- 



Common. 

 P. gramineus, L., var. spathulseformis, Robbins. 



Mystic Pond (Rev. Thos. Morong). 



P. gramineus, L., var. maximus, Morong. 



So. Natlck (Rev. Thos. Morong). 



" This variety generally occurs in swift currents, and differs from 

 the type in usually having all the parts much elongated, stems 5 to 

 10 ft. ill length, and the sessile or petiolate submerged leaves 3-7 

 lines wide by 2-5 inches long, and 7-10 nerved." Morong in litt. 



P. lucens, L. 



Fresh Pond (Rev. Thos. Morong) ; Winchester (L. L. Dame). 



P. Zizii, Mert. & Koch. (P. lucens, L., var. minor, BTolte, Man.) 

 Fresh Pond (Rev. Thos. Morong). 



P. praelongus, Wulf. 

 Fresh Pond (John Robinson, et al.) 



P. perfoliatus, L. 

 Mystic Pond (Wm. Boott) ; Fresh Pond (Dr. C. W. Swan). 



P. Mysticus, Morong. 

 Mystic Pond, Medford (Rev. Thos. Morong) . 



"The whole plant very slender; stems irregularly branching from 

 ' a creeping rootstock, nearly filiform, terete, 1-3 ft. high ; leaves all 

 submerged, scattered, entire, oblong-linear, Y^-'V/i inches long, and 

 2 or 3 lines wide, 5-7 nerved, finely undulate, obtuse or bluntly 

 pointed at the apex, abruptly narrowing at the base, and sessile or 

 partly clasping ; stipules free, obtuse, about 6 lines long, mostly 

 deciduous but often persistent, and closely sheathing the stem; 

 spikes few, capitate, 4-6 flowered, on erect peduncles from 1-2 inches 

 long. With the habit of P. perfoliatus, but scarcely y^ as stout in 

 any of its parts." Morong in Bot. Gaz., Vol. V., No. 5. 



