Lysimachia venosa is a shrub that grows 50–100 cm tall, possibly taller. The stems have brown, striate bark, with young stems being sparsely puberulent and soon becoming glabrate. The leaves are simple and alternate, well-spaced along the stem. The blades are oblanceolate, 60–110 mm long, and 16–30 mm wide. The leaf apex is acuminate, and the base is sessile, gradually tapering. The blades are coriaceous with minutely revolute margins. Lateral and tertiary veins are evident but not especially conspicuous. Petioles are 1–6 mm long. Stipules are absent. The flowers are solitary in the leaf axils and bisexual (perfect), actinomorphic (radially symmetric), and 6–7-merous. The pedicels are 15–30 mm long, glabrous or with a few minute hairs, and bracteate, but bracteoles are absent. The calyx comprises five sepals with narrowly lanceolate lobes 12–16 mm long and sparsely puberulent at the base. The corolla, with an unknown color, is 18–19 mm long, and the lobes are obovate and imbricate. There are as many stamens as there are corolla lobes; the filaments are connate for about one-third of their length and adnate to the corolla tube. The anthers are dithecal. The ovary is superior and 1-celled with free-central ovule placentation and a single style. The fruit and seed characteristics are TBD. It is found on steep cliffs at an elevation of approximately 1,560 meters.