J Syst Evol ›› 1991, Vol. 29 ›› Issue (5): 394-417.

• Research Articles • Previous Articles     Next Articles

On Circumscription of the Genus Cicerbita Wall., and Two New Genera of Compositae from Sino-Himalayan Region

Shih Chu   

  • Published:1991-09-10

Abstract: Dealt with in the present paper is a comparatively complex group of plants with an outermost ring of short pappus at the apex of achenes in the tribe Lactuceae of Compositae from the Sino-Himalayan Region. The group includes plants with rostrate achenes and those with achenes non-rostrate, neither broadened, nor thickened or both broadened and thickened margins as well as those with both heads polyanthous and plants with heads reduced to only 3 florets. The previous taxonomical treatments of the complex group may be considered unnatural. These non-Lactuca plants were treated either as members of the genus Lactuca, or as those of the genus Cicerbita. In order to provide a clear and natural classification for these extremely complex group of plants from the Sino-Himalayan Region, it is first necessary to clear up the concept of the genus Cicerbita. Cicerbita, as a genus, was separated from Lactuca and established by Wallarth as early as in 1822 based on Lactuca alpina etc., but its circumscription was unclear at the beginning. In his concept, Cicerbita covers not only plants with rostrate achenes, but also plants non-rostrate achenes. The concept of Cicerbita had not been clear until its lectotype was chosen. That is to say, only those plants with combination of non-rostrate achenes and an outermost ring of short pappus at the apex of achenes in the tribe Lactuceae can be regarded as the members of the genus Cicerbita. Such a concept of Cicerbita deffers not only from the one of B. Beauverd, who placed genera, such as Mycelis Cass., Mulgedium Cass., Steptorhamphus Bunge and Cephalorrhynchus Boiss., into Cicerbita respectively as section, but also from the one of G. L. Stebbins, who also used strict concept of Cicerbita. On the basis of the concept of Cicerbita mentioned above, through identification of specimens with an outermost ring of short pappus of the tribe Lactuceae in the Herbarium of Institude of Botany, Academia Sinica, recognized are four species from China in the genus, i. e. Cicerbita oligolepis Chang, sp. nov., C. tianschanica (Rgl. et Schmalh.) Beauverd, C. azurea (Ledeb.) Beauverd and C. sikkimensis (Hook. f.) Shih. With the concept of Cicerbita thus defined the related group of plants from the Sino-Himalayan Region can now be further treated. One of them, like the plants of Cicerbita, has an outermost ring of short pappus at the apex of achenes also, but by its Achenes with broadened and thickened margin, acute or acuminate, extending into a rostrum at its apex, the group differ not only from Cicerbita with erostrate achenes, but also from Lactuca without an outermost ring of short pappus at apex of achenes. Unfortunately, some species in the group of the Sino-Himalayan Region were placed in the genus Lactuca by predicessors. In fact, This is a new genus, Chaetoseris Shih. The genus Chaetoseris Shih seems to be more similar to Cephalorrhynchus Boiss with achenens neither broadened, nor thickened along its margins than to Cicerbita Wallr. All of 18 species of Chaetoseris Shih are distributed in the Sino-Himalayan Region. They are Chaetoseris grandiflora (Franch.) Shih, Ch. dolichophylla Shih, Ch. leiolepis Shih, Ch. taliensis Shih, Ch. macrantha (C. B. Clarke) Shih, Ch. ciliata Shih, Ch. hastata (Wall. ex DC.) Shih, Ch. cyanea (D. Don) Shih, Ch. macrocephala Shih, Ch. lyriformis Shih, Ch. hispida Shih, Ch. roborowskii (Maxim.) Shih, Ch. likiangensis (Franch.) Shih, Ch. sichuanensis Shih, Ch. pectiniformis Shih, Ch. lutea (Hand. -Mazz.) Shih, Ch. rhombiformis Shih and Ch. yunnanensis Shih Another group of Compositae which is represented by Lactuca graciliflora Wall. ex DC. etc. and distributed in the Sino-Himalayan Region, and has an outermost ring of short pappus at the apex of achenes, evidently should not be regarded as the members of Lactuca. With a combination of usually fine cylindrical, calyculate involucres, 3 phyllaries arranged in 1 row, and heads with 3 florets and achenes broadened and thickened along its margins the group should be regarded as a new genus, Stenoseris Shih. This new genus seems to be similar to Mycelis Cass., with achenes neither broadened, nor thickened along its margins and yellow florets rather than to Chaetoseris Shih. Stenoseris Shih, distributed in the Sino-Himalayan Region, has five species. They are St. graciliflora (Wall. ex DC.) Shih, St. taliensis (Franch.) Shih, St. tenuis Shih, St. leptantha Shih and St. triflora Chang. On the basis of the concept of Cicerbita, the present author provides in this paper a revision for plants in the Sino-Himalayan Region previously placed in Lactuca. In this sense, the present paper can be regarded as a continuation of “REVISION OF LACTUCA L. AND TWO NEW GENERA OF TRIBE LACTUCEAE (COMPOSITAE) ON THE MAINLAND OF ASIA” published in ActaPhytotaxonomica Sinica before.

Key words: Compositae, Lactuceae, Cicerbita, Chaetoseris, Stenoseris, Cephalorrhynchus