Bartonia lanceolata Small

Stems decumbent to erect or ± twining, yellowish green, prox­imally sometimes purplish, 10–52 cm. Flowers: calyx lobes dis­tinct nearly to base, 1.5–2.9 × 0.5–1 mm; corolla 2.9–6.2 mm, lobed 0.6–0.8 times its length; anthers yellow, 0.3–0.5 mm, apex rounded. 2n = 52.

Flowering summer–fall. Bogs, fens, white-cedar swamps, wet, open woods, peaty lake margins; 0–500 m; Ont.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Ky., La., Maine, Md., Mass., Mich., Miss., Mo., N.H., N.J., N.Y., N.C., Okla., Pa., R.I., S.C., Tenn., Tex., Va., Wis.

A specimen from Newfoundland identified as this subspecies was reidentified as subsp. iodandra in studies for this flora.

Molecular studies (C. Ciotir et al. 2013) of plants identified morphologically as subsp. paniculata disclose greater genetic divergence than expected between plants from the Atlantic coastal plain in New Jersey and the disjunct populations in the Great Lakes region, the latter clustering more closely with subsp. texana. If popula­tions in the interior were distinguished taxonomically, the epithet paniculata, whether at specific or infraspecific rank, would remain for the plants of the Atlantic coastal plain.