Veronica anagallis-aquatica L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Fibrous-rooted, probably biennial or short-lived perennial, ± erect, 2-10 dm, glabrous, or slightly glandular in the infl; lvs all opposite, mostly elliptic or elliptic-ovate to elliptic-oblong, sessile and mostly clasping (or the lower with subpetiolar base), 2-10 × 0.7-5 cm, 1.5-3 times as long as wide, sharply serrate to entire (sterile autumnal shoots with more rounded and petiolate lvs); racemes axillary, pedunculate, many-fld; sep highly variable in form and size; cor rather light blue, 5-8 mm wide; mature pedicels generally strongly ascending or upcurved, 3-8 mm; fr turgid, 2.5-4 mm, scarcely notched, nearly or fully as wide; style 1.5-2.5 mm; seeds numerous, 0.5 mm or less; 2n=36. Along ditches and slowly moving streams, or in other wet places, frequently in shallow water, but largely emersed; native of Eurasia, now established throughout our range. May-Sept. (V. glandifera) Hybridizes with no. 18 [Veronica catenata Pennell].