Abstract: The morphology of fruits in 16 species, one variety and one form of Polygonum
sect. Polygonum from China was studied under stereoscope and scanning electron microscope
(SEM). Fruits were observed heterocarpic in five species of the annuals of Polygonum sect.
Polygonum, viz., shorter fruits (shorter or sub-equal to persistent perianths) vs. longer fruits
(obviously longer than persistent perianths). Based on morphology of achene surface, fruits of
Polygonum sect. Polygonum can be divided into two types: (1) achenes smooth and shiny, but
not tuberculate or verrucate; (2) achenes scabrous, but not or slightly shiny, tuberculate or
verrucate. The first type includes two subtypes: (1) achenes shallowly waved, e.g., P.
cognatum, P. argyrocoleum and P. acerosum; (2) achenes with irregular hollows or stellate
plications, e.g., P. plebeium, P. polycnemoides and P. shiheziense. The second type includes
four subtypes: (1) achenes irregularly verrucate, e.g., P. intramongolicum; (2) achenes with
scattered tubercules, e.g., P. humifusum and the shorter fruits of P. patulum; (3) achenes with
tubercules standing in a queue, e.g., P. aviculare, P. tachengense and shorter fruits of P.
urumqiense; (4) achenes with tubercules scattered in upper part and hollows or stellate
plications in lower part, e.g., the longer fruits of P. aviculare, P. aviculare f. erectum, P.
patulum and P. rigidum. The heterocarpy and micro-morphological characteristics of fruits are
valuable to identify species and varieties in Section Polygonum. In this study, the systematic
position of Polygonum aviculare L. var. fusco-ochreatum (Kom.) A. J. Li was determined and
restated as Polygonum fusco-ochreatum Kom. and a new species, Polygonum huichunense F.
Z. Li, Y. T. Hou & C. Y. Qu, was described.

Key words: Fruit, heterocarpy, morphology, new species, Polygonum sect. Polygonum,