| Abstract: | Having mixed extremely various patterns of achenes for a long time inthe genus Lactuca L., especially showed in the classification of it on the mainland of Asia,Lactuca L., the primary unnatural genus, becomes more nuclear in its limit. The presentpaper makes a revision to attempt providing a clear cline between Lactuca L. and its relativegenera. On my opinion, only plants, represented by Lactuca sativa L., which have ovoid capitulum during its fruiting, numerous (7-25), yellow ligular florets and longitudinal 1-10 ribsor striae on each side of achenes, acute into filiform beak at its apex, should be defined asLactuca L. In view of the present concept of Lactuca L., another group of plants, embodied byLactuca indica L., having its broadening, thin winged-margin of, 1-3 striae on each side ofachenes, black, dorsi-ventral compressed, acute into thick and short beak at its apex, evidently, should not be placed into Lactuca L., but be regarded as genus, i.e. Pterocypsela Shih,gen. nov. Pterocypsela Shih distributes in Eastern and southern Asia, where Lactuca L. does not occur. In China there is all of species, seven species, of Pterocypsela Shih. They are P. raddeana (Maxim.) Shih, P. indica (L.) Shih, P. elata (Hemsl.) Shih P. lacciniata (Houtt.) Shih, P. triangulata (Maxim.) Shih, P. sonchus (Lévl.) Shih and P. formosana (Maxim.) Shih, But in Mediterranean regions and Middle and Western Asia mainly distributes Lactu ca L., in which there are only seven species from western China, Xijiang autonomic district. They are L. dolichophylla Kitam., L. sativa L., L. altaica Fisch. et Mey., L. serriola Torner, L. dissecta Don, L. auriculata DC. and L. undulata Ledb. With the combination of violet-purple ligular florets non-ovoid capitulum during its fruiting, a little thick achenes, acuminate into longer. or short beak at its apex and 4-6 ribs on each side of it, Mulgedium tataricum (L.) DC. is evidently different from Lactuca sativa L. with combination of ovoid capitulum during its fruiting, yellow ligular florets and compres sed achenes, acute into filiform beak at its apex. There seems to be no point in refusing Mu lgedium Cass. as a genus. Strictly speak, Mulgedium Cass. seems to be reminiscent of Para prenanthes Chang (see bellow) without beak at the apex of its achenes. In Hengduan moun tains and mountain range of Himalayas M. tataricum (L.) DC. discoveries its relative par tners. They are M. bracteatum (Mook. f. ex. C. B. Clarke) Shih, M. lessertianum (Wall. ex C. B. Clarke) DC., M. monocephalum (Chang) Shih, M. umbrosum (Dunn) Shih, M. meridionale Shih and M. polypodifolium (Franch.) Shih. Having broadering and thickening margin and 4-7 striae on each side of achenes, grey, dorsi-ventral compressed, truncate and beakless at its apex, Lactuca sibirica (L.) Benth. ex Maxim. (Sonchus sibiricus L.) is not only different from Lactuca sativa L. with the combination of yellow ligular florets and filiform beak at apex of its achenes, but also from the genus Mulgedium Cass. with beak at apex of its achenes. Therefore, Lagedium Sojak, established by J. Sojak (1961), should be restored. It should be point out that Lagedium Sojak is monotypic genus excluding Mulgedium tataricum (L.) DC. with beak at the apex of its achenes, non-marginated. Lagedium Sojak widely distributes in temperate and frigid zone ofvnorthern hemisphere. In our country, Lagedium sibiricum (L.) Sojak, sole species of the genus, restricts its northeast region. Paraprenanthes Chang, the new genus, established by Ch. Ch. Chang (1950) based on Lactuca sororia Miq. and Lactuca yunnanensis Franch. seems to be a distinct genus. This genus is characterized by 4-6 ribs on each side of achenes, black, fusiform, a little thick andbeakless at its apex. Besides above-mentioned two species, assigned by Chang, in forest of tropic and subtropic zones on the mainland of Asia there are many species with same structurein achenes like L. sororia Miq. and L. yunnanensis Franch. The genus Paraprenanthes Changseems to be reminiscants of Mulgedium Cass. and Lagedium Sojak, but differs from the formerin its beakless achenes, from the later in its non-marginated achenes and 4-6 ribs on eachside of it. In our country, there are all species of the genus known in the tropic and subtropic zones on the mainland of Asia. They are P. sororia (Miq.) Shih, P. yunnanensis (Franch.) Shih, P. longiloba Ling et Shih, sp. nov., P. heptontha Shih et D. J. Liou, sp. nov., P.prenanthoides (Hemsl.) Shih, P. pilipes (Migo) Shih, P. thirionii (Lévl.) Shih, P. sylvicolaShih., sp. nov., P. multiformis Shih, sp. nov., P. auriculiformis Shih, sp. nov. and P. sagittiformis Shih, sp. nov. |
