Taxonomic studies of Bistorta (Polygonaceae) in the Himalayas and adjacent regions (2). - Bistorta amplexicaulis (D.Don) Greene and its allies, with special reference to the ochreae and leaf sheathes of cauline leaves

Bistorta amplexicaulis (D.Don) Greene and its allies are taxonomically revised. Well-developed leaf sheathes of cauline leaves are considered as an apomorphic character in Bistorta, and B. amplexicaulis lacking such leaf sheathes is assumed as a primitive species in the genus. A new variety, B. amplexicaulis subsp. amplexicaulis var. dhorpatanensis Yonek. & H.Ohashi, is described from cenral Nepal. Bistorta amplexicaulis subsp. sinensis (Forbes & Hemsl.) Soják is regarded as a species distinct from B. amplexicaulis and a new name, B. henryi Yonek. & H.Ohashi, is proposed for it. Bistorta sinornontana (Sam.) Miyam. is reduced to a subspecies of B. amplexicaulis and a new combination, B. amplexicaulis subsp. sinomontana (Sam.) Yonek. & H.Ohashi, is proposed.