Yellow or Virginia or late-flowering bartonia, yellow screwstem, bartonie de Virginie

Sagina virginica Linnaeus, Sp. Pl. 1: 128. 1753; Bartonia tenella Willdenow

Herbs ± erect, yellowish green, often purplish proximally or occasionally more extensively, 3–45 cm. Leaves all opposite, proximal alternate and distal opposite, or rarely all alternate, closely spaced near base of stem, gradually more widely spaced distally; blade 0.9–4.7 mm. Inflorescences racemoid cymes or small thyrses with strongly ascending branches. Flowers: calyx lobed nearly to base, lobes lanceolate, 2–4.5 × 0.4–1.1(–1.4) mm, apex acuminate; corolla white to greenish white or yellowish green, distally or occasionally more extensively often purple-tinged especially in age, 2.3–4.4 mm, lobes oblong, 1.6–3.2 × 0.7–1.4 mm, that is, 0.6–0.8 times the length of the corolla, margins usually erose-serrate distally, apices rounded to abruptly acute, mucronate; anthers often recurving in age but not coiling, yellow or purple, 0.5–1.2 mm, apex mucronate to short-acuminate; style absent; stigmas decurrent along sutures of ovary. Capsules dehiscent medially. 2n = 52.

Flowering late summer–fall. Bogs, shores, mesic to wet, open woods, usually peaty soils; 0–500 m; St. Pierre and Miquelon; N.B., N.S., Ont., Que.; Ala., Conn., Del., D.C., Fla., Ga., Ill., Ind., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Vt., Va., W.Va., Wis.

Inrolling of margins during drying may cause the corolla lobes of herbarium specimens of Bartonia virginica to appear to taper more gradually than they actually do, leading to misidentification as B. paniculata.