Elatostema oppositum (Urticaceae), a New Species from Yunnan, China

A new species of Elatostema J. R. Forst. & G. Forst. (Urticaceae), E. oppositum Q. Lin & Y. M. Shui, belonging to section Weddelia (H. Schroet.) W. T. Wang ser. Stipulosa W. T. Wang, is described and illustrated from Yunnan Province, China. The new species was found on limestone rocks at altitudes of 1700-1940 m and differs from the other species in series Stipulosa by its paired staminate inflorescences that are opposite one another at the stem nodes (staminate inflorescences are solitary in the other species of Elatostema ser. Stipulosa) and by its pistillate inflorescences in pairs at the leaf base or opposite one another at the stem nodes (pistillate inflorescences are solitary in the other species of this series). The new species is related to E. nasutum Hook. f., but can be distinguished by its stems that are longitudinally striate, the paired staminate inflorescences opposite one another at the stem nodes, the pistillate inflorescences in pairs or opposite one another at the stem nodes, and the staminate flowers that are 5-merous.