A taxonomic study of the genus Hippolytia Poljak.

The present paper is an attempt to propose a preliminary taxomomic treatment ofthe genus Hippolytia Poljak. and to analyse the geographical distribution of its composite elements. This small genus with 17 species is divided into 2 sections, namely, sectionAnthodesma Shih and section Hippolytia. Anthodesma is a small section with 3 speciesand is characterized by fascicled corymbs, campanulate and nitid involucres, rigidlyherbaceous phyllaries, and undershrubs, while Hippolytia consisting of 14 species ischaracterized by corymbose inflorescence or glomerules or compund heads, cuneate andunpolished involucres, herbaceous phyllaries with pitch black margines. There are 12 species of Hippolytia in China, of which 3 are proposed as new in thepresent paper. Regarding the distribution pattern of Hippolytia, it is noteworthy to note that itsrange of distribution forms a more or less U-shape as shown in map 2. It may be seenthat Hippolytia distributes in Central Asia-Sino-Himalaya-Median Asia. Section Anthodesma Shih occurs in central Asia, while section Hippolytia in the whole Himalayanregion and northern Meridional Ranges and Median Asia. There seems to be no center of species concentration within the total range ofHippolytia, whose species are localized in distribution, for example, H. desmantha Shihis known only from Qinghai provence (Yu-Shu-Hsien), H. alashanensis (Ling) Shihis restricted to Ninghsia and central part of Kansu provence. It is interesting to notethat H. yunnanensis (J. F. Jeffrey) Shih and H. longifolia (Wall.) Shih are referredto as vicarious species. The localization of the species distribution and the obviousdiscontinuity of morphological characters between species indicate a remarkable geographical influence on the species formation of Hippolytia. Hippolytia is an alpine genus of temperate zone of Asia, in which 64 per cent ofspecies occurs at high elevations of above 3300m. altitude, 30 per cent of species aredistributed in middle elevations of above 2200m. altitude. The life forms are microundershrubs, erect perennial herbs, glomerule stemless herbs or stemless herbs. It is verypossible that its geographical origin and development may be linked up with occuranceof desert steppe, especially of alpine meadow vegetations in the northern temperatezone of Asia. With regard to the geographical elements to which each species of Hippolytiabelongs, it seems to indicate that H. trifida (Turcz.) Poljak., H. alashanensis (Ling)Shih and H. desmantha Shih belong to the geographical elements of central Asia,while H. yunnanensis (J. F. Jeffrey) Shih, H. glomerata Shih, H. tomentosa (DC.)Tzvel., H. senecionis (Bess.) Poljak. H. longifolia (Wall.) Shih, H. kennedayi (Dunn)Ling, H. syncalathiformis Shih, H. gossypina (Hook. f. et Thoms.) Shih and H. nana(C. B. Clarke) Shih to Himalayan elements, and H. darvasica (C. Winkl.) Poljak., H.megacephala (Rupr.) Poljak,, H. herderi (Rgl. et Schmalh.) Poljak. to Median Asia, H.delavayi (W. W. Smith) Shih to North-West-Yunna.