Veronica anagallis-aquatica, water speedwell

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Intermountain Flora
Aquatic rhizomatous perennial, 1-6 (10) dm tall; stems erect or ascending, simple to much-branched at the base; herbage glabrous; leaves somewhat clasping, 2-6.5 (8) cm long, 5-25 (40) mm wide, elliptic, 1.5-3 times as long as wide, the upper ones sessile, clasping, crenate-serrate, actue to acuminate, elliptic-lanceolate to ovate, the lower subpetiolate or sessile, oblanceolate to obovate, obtuse to acute apically, cordate, rounded or truncate basally; racemes axillary, glabrous to glandular-puberlent, often more than 30-flowered, the bracts reduced, lanceolate to linear; pedicels 4-8 mm long, upcurved or sometimes ascending; calyx 3-5.5 mm long, the segments broadly lanceolate; corolla 5-10 mm across, blue, pale violet with purplish guidelines; capsule both septicidal and loculicidal, usually slightly longer than broad, 2.8-4 mm long, 2.5-3.8 mm broad, plump, scarcely notched, the syle 1.5-3 mm long; seeds 0.3-0.5 mm long, more or less plano-conves, numerous; 2 n = 18, 36.

Cronquist, A., Holmgren, A.H., Holmgren, N.H., Reveal, J.L., and Holmgren, P.K. (1984) "Intermountain Flora" pg. 464, vol. 4, The New York Botanical Garden New York.