Annuals. Stem 10-65(-70) cm tall, erect, not rooting at nodes, with abundant 0.2-1.1 mm patent to retrorse nonglandular trichomes and scattered 0.2-0.7 mm patent glandular trichomes. Stipules lanceolate to subulate, distinct. Leaves 1-3 alternate but opposite at inflorescence; petiole with usually 0.2-1.1 mm patent nonglandular trichomes and scattered glandular trichomes; leaf blade 2.2-6.5 cm, palmately cleft, ratio of main sinus/middle segment length = 0.7-0.9, pilose with appressed nonglandular trichomes; segments 5(or 7), rhombic, 2-5 mm wide at base, 5-12-lobed in distal half, ratio of second sinus/middle segment length = 0.27-0.31. Cymules in dense aggregates at apex of each branch or solitary in forks, 2(or 3)-flowered; peduncle 0-2.5(-6) cm. Pedicel 3-11 mm, with 0.2-0.7 mm patent or sometimes retrorse but not appressed nonglandular trichomes and 0.3-0.6 mm patent glandular trichomes; bracteoles lanceolate. Sepals 5-6.5 mm, mucro 1.5-2 mm, ratio of mucro/sepal length = ca. 0.3, outside with 0.1-0.6 mm antrorse to patent nonglandular trichomes and 0.2-0.5 mm patent glandular trichomes, inside glabrous. Petals white or pale purple, 5.5-6 mm, erect to patent, inside glabrous, margin basally ciliate, apex rounded or slightly notched. Staminal filaments whitish, lanceolate to lanceolate with an abruptly narrowed apex, abaxially sparsely pilose and basal half ciliate, trichomes 0.1-0.3 mm; anthers yellowish, 0.4-0.6 mm. Nectaries 5, hemispheric, glabrous. Stigma pinkish. Fruit 1.9-2.5 cm, erect when immature; mericarps smooth, with a basal callus, with 0.5-1.8 mm patent to antrorse nonglandular trichomes and sometimes 0.4-1 mm patent glandular trichomes; rostrum 1.5-1.9 cm, with a 1-2 mm narrowed apex; stigmatic remains 0.7-1.4 mm. Seeds 2-2.2 mm. Fl. Apr-Jul, fr. May-Sep. 2n = 46-48, 52.
"Annual; stems several, freely branched, eventually to 6 dm, villous with spreading or somewhat retrorse hairs, and becoming glandular above, lvs rotund- reniform, 3–7 cm wide, deeply 5–9-cleft with oblong to obovate, deeply toothed or lobed segments; peduncles mostly 2-fld, the pedicels to twice as long as the cal; sep to 1 cm, short-awned, equaling the retuse pet; fr 2–5 cm, the stylar beak 1–2 mm, the carpel-bodies hirsute with long antrorse hairs ca 1 mm; seeds very obscurely reticulate; 2n=52. Dry, barren or sandy soil and waste places; Me. to B.C., s. to Fla., Tex., and Calif. May–Aug. Var. carolinianum, chiefly southern, but extending n. to Mass. and Mich., has a relatively loose and open infl; var. confertiflorum Fernald, the common form in our range, has very short upper internodes, the fls thus in compact, many-fld, umbel-like terminal clusters. (G. sphaerospermum Fernald, plants with seeds of maximum plumpness and sep of maximum width—an unusual combination)"