Planera aquatica (Walter) J.F.Gmel.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Tall shrub or small tree to 10 m; lvs lance-ovate to oblong or ovate, usually 3–7 cm, rounded at base, glabrous to minutely pubescent; staminate fls barely protruding from the bud-scales; pistillate fls 1–3 from each axil; fr conspicuously stipitate above the persistent cal, the endocarp thin and papery, the exocarp raised into longitudinal ridges bearing soft, finger-like projecting processes 1–3 mm. Swamps; Fla. to Tex., n. to w. Ky., s. Ill. and s. Mo. Fls with the lvs, April.