Notes on Paeonia decomposita Hand.-Mazz.

Abstract

Summary. Paeonia decomposita, regarded as endangered in the China Plant Red Data Book, has been found to be rather common in a restricted area of NW Sichuan. Two subspecies with distinct geographical distributions can be distinguished. One of these, P decomposita subsp. rotundiloba, is described as new and illustrated here. Plants conspecific with the collections from the Mingjiang Valley were found in seven additional localities in the valley. Further collections were also made of the taxon from the Daduhe Valley. The two differ in the number of carpels and in leaflet shape. Sixty-two individuals from six populations in the Daduhe Valley were examined. One individual had four carpels while all the rest had five. Carpel number in the Mingjiang Valley populations varied from two to five (Table 1). Leaflets from the two populations differ in size, shape, and lobing (Fig. 1). The Mingjiang populations have wider and shorter leaflets which are acute or obtuse at the apex, rather than acuminate as in the Daduhe plants. The ratios between leaflet and lobe length and width are almost discontinuous between the two populations (Fig. 2). In view of this, subspecific rank seems most appropriate for the two populations.