Myriophyllum sibiricum Kom.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Stems loosely erect in the water, often whitish, not much branched above, not much thickened below the infl; shoot-tip knob-like, with crowded lvs, the internodes mostly ca 1 cm or less; lvs whorled, 1–5 cm, with mostly 5–12 slender, widely arcuate segments to a side; spikes emersed, mostly 4–10 cm, with whorled bracts and fls, the fls at the lower nodes pistillate, at the upper staminate; lower bracts mostly serrate or somewhat pectinate-toothed, to about as long as the frs, the upper (subtending the staminate fls) entire and oblong-spatulate or ovate-oblong; pistillate fls without perianth, or the sep vestigial and under 0.5 mm; staminate fls with small pinkish pet; stamens 8; mericarps ca 2 mm, smooth or nearly so; plants in late season developing axillary (and often terminal) dark green turions 2+ cm, these eventually separating from the parent plant by decay, the new plants with a characteristically curved or U-shaped stem-base; 2n=42. In circumneutral to alkaline water; Lab. to Alas., s. to Md., Va., W.Va., Ill., Mo., N.M., and Calif.; also in n. Eurasia. (M. exalbescens)