Annual herb 10 - 40 cm tall Stem: delicate, wiry, erect, yellowish green, and unbranched below the inflorescence. Leaves: more or less opposite, stalkless, and reduced to tiny, narrow scales, less than 3 mm long. Flowers: yellowish, tiny (3 - 4 mm long), and arranged on short stalks along the main stem or ascending branches. The radially symmetric flowers have four sepals, four petals, about 0.5 - 1 mm long anthers, a single-chambered superior ovary, and an almost nonexistent style. Fruit: a small, single-chambered capsule.
Similar species: Bartonia virginica is the only species of this genus in the Chicago Region. However, B. paniculata, which occurs more south and east (especially along the Atlantic Coastal Plain), is quite similar except it has the leaf scales alternate at least in the middle of the stem, and the anthers are smaller (0.3 - 0.5 mm long).
Flowering: July to September
Habitat and ecology: Uncommon or even rare overall, primarily in sphagnum bogs and swales, acid and peaty edges of low moist sands, and sometimes moist woods or thickets.
Occurence in the Chicago region: native
Etymology: Bartonia is named after the Philadelphia botanist, Benjamin Smith Barton. Virginica refers to the plant being "of Virginia" in the wide sense, that is from the eastern United States.
Author: The Field Museum
From Flora of Indiana (1940) by Charles C. Deam
Infrequent in the lake area and very rare south of it. Usually found in clumps of sphagnum in bogs and more rarely in moist habitats in very sandy, minimacid soil in open places in black and white oak woods, growing in moss with Polygala cruciata, Gaultheria procumbens, and Aronia melanocarpa.
Stem simple to the infl, erect, 1-4 dm; lf- scales usually opposite; infl racemose or paniculate, the branches and pedicels commonly opposite and erect; fls 3-4 mm; sep lance-subulate; pet oblong, usually denticulate, abruptly narrowed to a rounded or obtuse, often mucronate tip; anthers minutely apiculate; 2n=52. Sphagnum bogs and wet meadows; Que. and N.S. to Wis., s. to Fla. and La. Late summer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.