Trees, deciduous, dioecious; . Leaves alternate, simple; stipules absent; petiole present; blade margins serrate; venation pinnate. Inflorescences unisexual, axillary, fascicles, (staminate) or flowers solitary (pistillate. Flowers unisexual; hypanthium absent; sepals 0; petals 0; nectary absent; stamens 5–12, distinct; anthers dehiscing by longitudinal slits; pistil 1, 2-carpellate; ovary superior, 1-locular; placentation apical; ovules 2 per locule, anatropous; style 0; stigmas 2. Fruits samaras. Seeds 1 per fruit.
Trees deciduous, dioecious. Sapwood and bark containing latex. Buds ovoid; scales deciduous. Leaves alternate, spirally arranged, exstipulate, petiolate; leaf blade simple, usually elliptic, sometimes somewhat ovate, obovate, or oblong, containing latex (forming strands if blade is transversely broken and pulled apart), pinnately veined, base rounded or cuneate-rounded, margin densely serrate with gland-tipped teeth, apex abruptly narrowed into an acuminate tip. Flowers axillary, borne near base of current year’s branchlets, very shortly pedicellate, without perianth, wind pollinated. Male flowers clustered; stamens 5–12, linear; filaments very short; anthers basifixed, 4-locular, dehiscing by longitudinal slits; connective slightly prolonged. Female flowers solitary: ovary stipitate, composed of 2 connate carpels, 1-locular, elongate, compressed, glabrous, apex 2-lobed; stigmas 2, decurrent, reflexed-spreading; ovules 2, collateral, anatropous, 1 aborting. Fruit an indehiscent samara, long elliptic to narrowly oblong, compressed, winged around margin; wing gradually narrowed at base into stipe, shortly 2-lobed at apex with sinus stigmatic; pericarp thinly leathery. Seed 1, linear, compressed, rounded at both ends; testa membranous; endosperm copious; embryo erect, large; cotyledons compressed, fleshy.
SELECTED REFERENCES Call, V. B. and D. L. Dilcher. 1997. The fossil record of Eucommia (Eucommiaceae) in North America. Amer. J. Bot. 84: 798–814. Vincent, M. A. 2002. Eucommia ulmoides (Hardy rubber-tree, Eucommiaceae) as an escape in North America. Michigan Bot. 41: 141–145. Zhang, Y. L., Wang F. H., and Chien N. F. 1988. A study on pollen morphology of Eucommia ulmoides Oliver. Acta Phytotax. Sin. 26: 367–370.
|Hardy rubber-tree Family|