96 NAIADACEAE 
slightly heart-shaped at base, about 4 as large as those of P. natans. 
Still waters, most of our area. 
3. P. pulcher, Tuckerm. Spotrep PonpwEeEp. Floating leaves large, 
3 to 5 in. long, 1 to 3 in. wide, oval, generally heart-shaped at base. 
Leaf stalks rather short. Flower stalk longer and spotted. Submersed 
leaves of two kinds, the upper lance, almost ribbon-shaped, 3 to 8 in. 
long, thin, pelucid, the lower broader, thicker and on a leaf stalk. Fruit 
3 ridged. Lakes and ponds, north to south in our area. 
Sec. 2. Floating leaves not heart-shaped. 
A. Submersed leaves expanded to somewhat broad leaf blades. 
4. P. amplifolius, Tuckerm. (Fig. 2, pl. 4.) LARGE-LEAVED Ponp- 
WEED. Floating leaves (not always present) oval or broadly elliptic, 
rounded at base 2 to 4 in. long. Submersed leaves broader and longer 
(4 to 8 in. long), with short leaf stalks, Stipules very long, grass-like. 
Lakes, especially in northern half of our area. 
5. P. alpinus, Balbis. (Fig. 5, pl. 4.) Nortuern Ponpweep. Float- 
ing leaves 2 to 5 in. long, often absent, lance-shaped, with apex broadest 
narrowing to a very short leaf-stalk. Submersed leaves much the same 
form, but with almost no leaf-stalks. Stipules broad, obtuse at free 
extremity. Flower stem 2 to 8 in. long, spike of flowers 1 to 13 in. long. 
Fruit reddish. Ponds and borders of streams, our area. 
Var. Faxoni, Morong. Faxon’s Ponpweep. Floating leaves rather 
shorter and broader than No. 6, and with very blunt points. Submersed 
leaves broader and with leaf-stalk 4 to 1 in. long. Creeks entering Lake 
Champlain from the east. 
6. P. lonchites, Tuckerm. LOoNG-LEAVED PONDWEED. (P. americanus, 
C. & S.) Floating leaves thin, opposite, elliptic, blunt or somewhat acute 
at apex, 2 to 6 in. long with long leaf stalks. Submersed leaves long, 
ribbon-like, wavy, acute at each end with leaf stalk 1 to 4 in. long. 
Stipules acute, 1 to 4 in. long. Fruit with 3 distinct ridges on the back. 
Ponds and streams. 
B. Submersed leaves narrowed to grass-like blades, not thread-like. 
7. P. heterophyllus, Schreb. Vartous-LEAVeD PoNnpweep. Stems 
very long and slender. Floating leaves 1 to 2 in. long, broad, elliptic, 
sometimes approaching to heart-shaped at base, pointed at apex. Leaf 
stalks 1 to 4 in. long. Submersed leaves narrow lance-shaped or linear, 
acute at both ends, rather stiff, no leaf stalk. Stipules long, broad at 
base, obtuse at outer extremity. A very variable species as the name 
indicates. Common, 
8. P. spathulaeformis, Morong. SPATULATE-LEAVED PoNDWEED. Float- 
ing leaves broadly elliptic or ovate, with the external extremity broadest, 
apex sharp pointed. Submersed leaves lance-shaped broader at outer ex- 
tremity and tapering to a short leaf stalk, stipules obtuse. Mystic Pond, 
Medford Pond, Mass. (said to be hybrid of P. heterophyllus and P. Zizii). 
9. P. Nuttallii, Cham. & Sch. (Fig. 3, pl. 4.) Nurrari’s Ponpwerp. 
(P. epiphydrus, Raf.) Floating leaves oblong, 1 to 4 in. long, tapering 
