7. Potamogeton confervoides Reichenbach in H. G. L. Reichenbach et al., Icones florae germanicae et helveticae. 7: 13. 1845.
Alga pondweed, Tuckerman’s pondweed, potamot confervoide
Potamogeton tuckermanii J. W. Robbins ([as tuckermani)]
Rhizomes obvious. Cauline stems terete, without spots, 10--80 cm. Turions present, in axils of old leaves and from disintegrating branches, fusiform, 0.7--2 cm, leaves spreading to ascending. Leaves submersed, ± spirally arranged, flaccid, sessile; stipules deliquescent, inconspicuous, convolute, free from blade, pale green, not ligulate, 0.5--1.2 cm, not fibrous, not shredding at tip, apex obtuse; blade pale green, linear, not arcuate, 1.8--6.5 cm ´ 0.1--0.5 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, extremely attenuate, bristly, lacunae present, each side of midvein to margins; veins 1. Inflorescences unbranched, emersed; peduncles not dimorphic, terminal, ascending, somewhat clavate, (3--)5--25 cm; spikes not dimorphic, capitate, 5--12 mm. Fruits sessile, light green, round-obovoid or nearly orbicular, compressed, abaxially and laterally keeled, 2--3 ´ 1.7--2.8 mm, lateral keels without sharp point; beak erect, 0.5 mm; sides without basal tubercles; embryo with less than 1 full spiral. Chromosome number apparently unknown not available.
Flowering early--late summer. Acidic waters of bogs, ponds, and lakes, often at higher elevation in e portion of range; 0--1500 m; St. Pierre and Miquelon, St. Pierre; N.B., Nfld. and Labr., N.S., Ont., Que.; Conn., Maine, Mass., Mich., N.H., N.J., N.Y., N.C., Pa., R.I., S.C., Vt., Wis.
Potamogeton confervoides is most uncommon and found only in fairly acidic waters. It is easily recognized by its linear, bristly leaves and the unusually long peduncle that seems out of place on a plant with such fine leaves. The leaves are so fine that they almost appear as greenish colored hair in the water. When the plant is removed from the water, the leaves are extremely flaccid leaves and essentially collapse onto each other.