Fagopyrum luojishanense, a New Species of Polygonaceae from Sichuan, China

Fagopyrum luojishanense J. R. Shao, a new species of Fagopyrum Mill. (Polygonaceae), is described and illustrated from Liangshan in Sichuan Province, China. This species is distinguished by its leaf blades that are ovate, narrowly ovate or triangular, winged seeds, and inflorescences that are either axillary or terminal, and we further distinguish the new species based on karyotype analysis. Fruit surface ornamentation of F. luojishanense is densely and irregularly warty, while fruit ornamentation is sparser in F. gracilipes (Hemsl.) Dammer ex Diels. Fagopyrum luojishanense is a diploid taxon, with 2n = 2x = 16 and a karyotype of 16 metacentric chromosomes, while F. gracilipes is tetraploid, 4n = 4x = 32, with a karyotype of 30 metacentric and two submetacentric chromosomes.