Flora of North America species comparison

erect, simple or few-branched, (7–)9–21(–29) cm, glabrous or glabrate proximally, glabrate or glandular-puberulent distally.

decumbent to ascending or erect, glabrous or glandular-hairy.

dimorphic, submersed basal and clustered, floating paired at ends of branches to 70 mm, blade of submersed lanceolate to oblanceolate or oblong, 1–7 × 0.5–3 mm, margins entire, apex obtuse to acute, surfaces glabrous, blade of floating elliptic to ovate or nearly round, 3–10 × 2–9 mm, margins entire, apex obtuse to rounded or retuse, surfaces glabrous.

cauline (also basal and clustered in G. amphiantha), opposite, monomorphic (dimorphic in G. amphiantha);

petiole absent;

blade not fleshy, not leathery, margins entire or toothed, surfaces often glandular-punctate.

axillary, flowers 1 or 2 per node;

bracts present.

stout, 0.1–3 mm, length less than 0.1 times bract, glabrous;

bracteoles 0.

present, sometimes short;

bracteoles present or absent, sepal-like.

sepals connate proximally, calyx lobes obovate to oblong, 0.7–1 mm;

corolla 3–4 mm, tube and limb white tinged pink or purple, veins lavender or purple;

style 0.5–1 mm.

bisexual;

sepals 5, distinct or proximally connate, calyx ± bilaterally symmetric, campanulate, lobes (sepals when distinct) linear to lanceolate, obovate, or oblong;

corolla white, cream, or yellow, sometimes pinkish, tube yellowish, brownish, or purplish, often with dark veins, bilaterally symmetric, bilabiate, tubular, tube base not spurred or gibbous, lobes 5, abaxial 3, adaxial 2, nearly completely connate and appearing as 1 emarginate lobe, throat glabrous or pubescent;

stamens 2, medially adnate to corolla, filaments glabrous, pollen sacs perpendicular to filaments, connective dilated;

staminodes 0 or 2, minute;

ovary 2-locular, placentation axile;

stigma capitate or lamelliform.

capsules, dehiscence septicidal, sometimes also loculicidal.

bilaterally symmetric, obcordiform, 2–3 × 3–4 mm.

(0.3–)0.4–0.5 mm.

ca. 200, yellow to brown or black, oblong to obpyramidal or short-cylindric, wings absent.

= 18.