Trailing loosestrife

Nummularia radicans (Hooker) Kuntze; Steironema radicans (Hooker) A. Gray

Stems reclining, trailing, or decumbent (sometimes rooting at nodes), simple or branched, 3-10.5 dm, glabrous or sparsely stipitate-glandular; rhizomes ± slender; bulblets absent. Leaves opposite; petiole 0.5-4 cm, ciliate proximally, cilia 0.2-0.9 mm; blade lanceolate to ovate-lanceolate, 2-10 × 0.5-3 cm, base rounded or obtuse to cuneate, decurrent, margins entire, plane, ciliolate (or rarely finely papillate or sometimes eciliolate), apex acute to acuminate, surfaces not punctate, glabrous; venation pinnate-arcuate. Inflorescences axillary, solitary flowers (rarely leafy racemes). Pedicels 1-3 cm, glabrous. Flowers: sepals 5, calyx sparsely or not streaked with resin canals, 2-5 mm, glabrous, lobes lanceolate, margins thin; petals 5, corolla yellow with reddish base, sparsely streaked with scattered dark resin canals (sometimes obscure), rotate, 2-6 mm. lobes with margins entire or erose apically, apex apiculate, stipitate-glandular adaxially; filaments apparently distinct or connate at very base, shorter than corolla; staminodes 0.4-1 mm. Capsules 2.5-5 mm, not punctate, glabrous. 2n = 34.

Flowering summer. Cypress and tupelo swamps, flood plains, stream banks, marshes; 0-200 m; Ala., Ark., Fla., Ill., Ky., La., Md., Miss., Mo., Okla., Tenn., Tex., Va.