Persicaria zhenaiguoi (Polygonaceae, Persicarieae), an overlooked new species from Dabie Mountains, central China

Persicariazhenaiguoi Bo Li, a remarkable new species discovered from the summit of Tiantangzhai Peak of Dabie Mountains in Hubei Province, central China, is described and illustrated. Based on its spicate inflorescences, ciliate ocreae, and the absence of prickles, the species is placed in P.sect.Persicaria. Within this section, P.zhenaiguoi most resembles P.orientalis and P.viscosa in gross morphology, particularly in the presence of densely spreading villus throughout. However, the new species can be easily distinguished from these two similar taxa by its nearly sessile leaves, which are lanceolate in shape with broadly cuneate to rounded bases, membranous ocrea with a small circle of green leaf-like wing, sparse and interrupted inflorescences, glabrous peduncles, greenish tepals, and ovoid achenes with grooved surfaces. Diagnostic characteristics, along with comparative photographs of the three related species, are provided, as well as a detailed morphological description and information on the distribution and habitat of the new species.