The Taxonomic Study Of The Genus Malus Mill.

The genus Malus Mill. has been studied for more than 250 years since the genus was established by Miller in 1754, and more than 500 taxa were published. A comprehensive and systematic study on the genus Malus Mill. of the world was carried out, based on the classical morphological taxonomy, associated with submicroscopic characters of leaf epidermis and seed coat, and materials from cytology, pollen morphology, plant biochemistry and molecular systematic study reported before. Type specimen and photos of type specimen were checked, more than 4 000 number of specimen from main herbaria of China were checked, and almost 20 000 specimen photos were shot. A series of field investigation and collection were carried out in Baokang and Shennongjia Natural Reservation Region of Hubei Prov., Lijiang and Kunming of Yunnan Prov., Mt. Ohmei of Sichuan Prov., Mt. Tianmushan of Zhejiang Prov., Mt. Taishan of Shandong Prov. and Mt. Huangshan of Anhui Prov. As a result, 22 wild species and 32 inner species taxa, 21 cultivated species were recorded in this paper. 7 new varieties were found, 11 taxa were combined or transferred as inner species taxa, 35 new synonyms and more than 130 invalid names or nude names were recorded, epithets of 3 species were replaced for early names, 2 new distribution species for Sichuan and Anhui Prov. were found, lectotypes or neotypes of 11 species or inner species taxa were designed, and many mistakes on suffix of epithets or nomenculature were corrected. Main researching results were as following: 1. The inner generic taxonomic system was thoroughly emended, 1 new subgenus and 1 new nothosubgenus, 2 new sections and 3 new nothosections, 2 series and 1 nothoseries were established; the scientific name of Sect. Gymnomeles Koehne was emended, 2 series were transferred to another section, etc. Parallel arrangement of native species and cultivated species in the system was adopted for the first time, instead of confusing them in a system or arranging them in two seperated frames. 2. Submicroscopic characters of the epidermis of leaves and seeds coat were studied for the first time. Both of them were found well prompting the evolution direction, and being great helpful in dividing subgenera and sections. The epidermis of leaves was also studied by optical microscope, the frame type of stomas and arrangement of epidermic cells was found helpful in taxonomy of the genus. 3. Geographical distribution and flora characteristics were thoroughly studied for the first time. The diversity center and the original center were concluded according to the analysis of flora data. 4. The importance of the morphologic characteristics was analyzed on the equability and aberrance. The character of apex of fruit core liber or connate was adopted to divide subgenera for the first time. The types of inflorescenses, shapes of fruits, deciduous or persistence of calyx, grit-cell, hairs of styles, vernations of leaves were suited for the divide of sections. The evidences of chemistry component and molecular analysis were regarded as very important ones for the dividing of subgenera and sections. 5. The name M. pumila Mill. was confirmed as the name of cultivated apple, but because M. domestica Borkh. has been well used by horticulturists, the name changing will cause disadvantageous nomenclatural change. So the author of this thesis had submitted a proposal to Taxon for conserving the name M. domestica Borkh. and rejecting M. pumila Mill. 6. 3 keys were compiled by characters of vegetable organs, flowers and fruits to fit the order in different periods.