Shetland Pondweed

Potamogeton rutilus Wolfg.; R. & S. Syst. Veg
Mant. 3 : 362. 1827.
Stem slender, much branched, without propagating buds ; leaves all submerged, capillary; with 2 glands at the base, 2.5-4.6 cm. long, 0.2-0.7 mm. wide, acute or more or less pungent at the apex, 3-5-nerved, the midrib often compound ; stipules acute, 1-2 cm. long, or often longer than the inter nodes, axillary and free from the leaf -bases, sometimes splitting into shreds; spikes scarcely 1 cm. long, few-flowered, sometimes interrupted; peduncles as thick as the stem, 1-2.3 cm. long; nutlets smooth, without keels but sometimes obscurely grooved ; embryo an incomplete spiral, the straight apex pointing outside the
base.
Type locality : Vilna, Russia.
Distribution : Quebec to Lake Superior, south to New York.