Monoecious trees to 30 m. Twigs purplish, glabrate. Leaves glandular at first, cordate, 5- or 7-lobed up to 1/2-way to the midvein, 6–20 cm wide, deeply toothed, deep green; petioles with white sap. Inflorescence erect panicles from short, side shoots. Flowers unisexual, yellow; sepals 4–5 mm long; petals 3–5 mm long. Samara 30–55 mm long, the seed 10–15 mm long (
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).