1. Eucommia ulmoides Oliver, Hooker's Icon. Pl. 20: plate 1950. 1890.
Hardy rubber-tree Hardy rubber-tree
Trees to 20 m; bark gray-brown, ridged and furrowed; branchlets brown, hairy when young, becoming glabrate, pith septate. Leaves: petioles 1–2.5 cm; blades elliptical to ovate, 5–20 × 2.5–8 cm, base usually truncate to broadly cordate or cuneate, sometimes oblique, apex acuminate, surfaces hairy when young, soon glabrate; latex strands visible in carefully torn leaf. Staminate flowers: anthers 10–12 mm. Pistillate flowers: pistil 10–12 mm. Samaras brown, 25–32 mm, apex emarginate. Seeds 12–15 × 3 mm. 2n = 34.
Flowering (Mar–)Apr. Disturbed woods, fence rows; 200–300 m; introduced; Ind., N.Y., Ohio; Asia (China); introduced widely.
Eucommia ulmoides, first reported as an escape in North America by M. A. Vincent (2002), has been put to many uses, including lumber, firewood, and a medicinal tonic (duzhong or tu-chung) made from the bark (T. Forrest 1995; D. J. Mabberley 2008; C. S. Sargent 1913–1917). Leaf and stem extracts have been shown to have potential medicinal value (H. J. Jeon et al. 1998; Y. Li et al. 1998; K. Metori et al. 1997, 1998; T. Nakamura et al. 1997; Y. Nakazawa et al. 1997). Eucommia ulmoides contains a latex (gutta-percha) that has been used in China for lining oil pipelines, insulating electrical lines, and filling teeth (Mabberley).
Eucommia ulmoides is sometimes used as a street or lawn tree. It is drought resistant, disease-free, and easily propagated by seed or cuttings; it is hardy in USDA Zones 4–7 (M. A. Dirr 1990; A. J. Rehder 1940).