4. Potamogeton Pulcher Tuckerm. Spotted Pondweed

Fig. 177

Potamogeton pulcher Tuckerm. Am. Journ. Sci. 45: 38. 1843.

Stems simple, terete, black-spotted, 1°-2° long. Floating leaves usually massed at the top on short lateral branches, alternate, ovate or round-ovate, subcordate, 2'- 4 1/2' long, 9"-3 1/4' wide, many-nerved; peduncles about as thick as the steam, 2'- 4' long, spotted; submerged leaves of 2 kinds, the uppermost pellucid, lanceolate, long-acuminate, undulate, 3'-8' long, 6"- 18" wide, tapering at the base into a short petiole, 10-20-nerved; the lowest much thicker, opaque, spatulate, oblong or ovate, on petioles '-4 long; stipules obtuse or acuminate, 2-carinate; fruit 2"-2i" long, 1 1/2" thick, turgid, tapering into a stout apical style, the back sharply 3-keeled; face angled near the middle, with a sinus below; embryo coiled.

In ponds and pools, Massachusetts to Georgia and Arkansas. July.

5. Potamogeton Epihydrus Raf. Nuttall's Pondweed

Fig. 178

Potamogeton epihydrus Raf. Med. Repos. II. 5: 354.

1808. Potamogeton Nuttallii Cham. & Schl. Linnaea, 2:

226. pl. 6. f. 25. 1827. Potamogeton Claytonii Tuckerm. Am. Journ. Sci.

45: 38. 1843.

Stems slender, compressed, 1- 6 long. Floating leaves opposite, elliptic to obovate, obtuse, sbort-petioled, 1 1/2' - 3 1/2' long, 4"-12" wide, many-nerved; submerged leaves linear, 2-ranked, 2.'-7' long, 1"-3" wide, 5-nerved, the 2 outer nerves nearly marginal, the space between the 2 inner and the midrib coarsely reticulated; stipules obtuse, hyaline, not keeled; peduncles 1'-5' long; spikes 1/2'-l' long; fruit round-obovoid 1 1/4"-2" long, 1"-1 1/2" thick, 3-keeled, the sides flat and indistinctly impressed; style short, apical; embryo coiled one and one-third times.

In ponds and streams, Newfoundland to British Columbia, North Carolina and Iowa. Creek-grass. June-Aug.

5 Potamogeton Epihydrus Raf Nuttall s Pondweed 178

6. Potamogeton Alpinus Balbis. Northern Pondweed

Fig. 179

Potamogeton alpinus Balbis, Misc. Bot. 13. 1804. Potamogeton rufescens Schrad.; Cham. Adn. Fl. Ber. 5. 1815.

Plant of a ruddy tinge; stems simple or branched, somewhat compressed. Floating leaves spatulate or oblanceolate, obtuse, many-nerved, tapering into petioles 1'-5' long; submerged leaves semi-pellucid, the lowest sessile, the uppermost petioled, oblong-linear or linear-lanceolate, obtuse or rarely acute, narrowed at the base, 3'-12' long, 2"-9" wide, 7-nerved; stipules broad, faintly 2-carinate, obtuse or rarely acute; peduncles 2'-8' long; spikes 1'-1 1/2' long; fruit obovoid, lenticular, reddish, 1 1/4" long, 1" thick, 3-keeled, the middle keel sharp, the face arched, beaked by the short recurved style; apex of the embryo pointing directly to the basal end.

In ponds, Labrador to British Columbia, Florida and California. Also in Europe. July-Aug.

6 Potamogeton Alpinus Balbis Northern Pondweed 179