Abstract: Pinellia ternata (Thunb.)Breit. (Araceae)is a perennial herb widely distributed in East Asia. It is common in the suburbs of Nanjing. Recently, another species of the same genus has been found in a Nanjing suburb. It resembles P. ternata in general appearance, but never possesses terrestrial bulbils which are characteristic of that species. Morphologically, it is more similar to P. yaoluopingensis X. M. Guo et X. L. Liu, a new species recently found in Anhui, than to P. ternata. The present paper deals with a comparative study of the variation pattern of two entities at the population level in order to elucidate their biological relationships. The following research work was carried out: (1)field investigation of the population sites; (2)mass sampling of natural populations for quantitative analysis, two populations (Population I & II) for P. ternata and one (Population III) for P.yaoluopingensis, aff.; (3) SEM observation of pollen grains; (4)examination of somatic chromosome numbers. As a result of the above observations, it was found that: I. Measurements of the quantitative morphological characters (Table 1 & 2) show that Population III differs remarkably from Populations I & II, but matches the original description of P.yaoluopingensis except for its lacking of small tubers. SEM micrographs of pollen grains (Plate 1 )show that Populations I & II are very similar to each other, but different from Population III both in morphology and in size. The overall morphological relationships among these three populations are shown in Fig. 2. II. The habitats of Populations I & II, though rather different in moisture and light conditions, are similar with respect to human disturbance, and quite different from that of Population III. Pinellia ternata shows some weedy characteristics. It occurs in hedgegrows and shady man-made groves. The vigorous vegetative reproduction by terrestrial bulbils producing clones of P.ternata has evidently anabled the plant become successfully adapted to its varied environments. III. Cytological investigation shows that both somatic chromosome numbers of Populations I & II (P.ternata) are 2n = 72 (Plate 2-1 & 2), inconsistent with all previous records (2n=28, 115, 116, 128). It appears to be an aneupolyploid. The chromosome number of Population III (P.yaoluopingensis, aff.)is 2n=26 (Plate 2-3). It is probably a diploid. Two problems deserve further study: (a) Is Population III identical with Pinellia yaoloupingensis or a new variation form of that species? (b) Has P. ternata originatedfrom the outbreeding P. yaoloupingensis?

Key words: Pinellia, Variation Pattern, Population, Nanjiang