Plant Syst. Evol. 227: 123-136 (2001)

Plant Systematics and Evolution

Cytogeography and taxonomy of the Paeonia obovata polyploid complex (Paeoniaceae)

D.-Y. Hong¹, K.-Y. Pan¹, and G.-Y. Rao²

(1) Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, China

(2) College of Life Science, Peking University, Beijing, China

Received October 30, 1998 Accepted June 21, 2000

Abstract. The taxonomy of the Paeonia obovata polyploid complex in E-Asia has been controversial with treatments ranging from one species and two varieties to five species and numerous infraspecific taxa. Extensive observations in the field, analysis of morphological characters based on 32 populations sampled, and the examination of a large amount of herbarium specimens show that all the characters used by previous authors for distinguishing the species are variable between or even within populations: Leaf position, petal colour, stamen number (from 21 to 110 in the red-flowered and from 58 to 239 in the white-flowered form), filament and anther colour, style length as well as follicle number and position. Therefore, all these characters are of no value for species delimitation. However, an extensive chromosome survey and the analysis of morphological characters show that the ploidy level is basically correlated with the geographical distribution and with the indumentum on the lower leaf surface. Thus, the recognition of one species with two subspecies is proposed: Paeonia obovata subsp. obovata, mostly diploid, widely distributed in the north, east and south of the distribution range and glabrous to sparsely pubescent or hirsute on the lower leaf surface, and subsp. willmottiae, tetraploid, limited to the west and with leaves densely hirsute or pubescent below.

Key words: Paeoniaceae, Paeonia obovata polyploid complex, morphological variation, cytogeog-raphy, taxonomic revision.

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