NICROSPOROGENESIS OBSERVATION AND KARYOTYPE ANALYSIS OF SOME SPECIES IN GENUS JUGLANS L.
核桃属部分种的小孢子发生及核型研究

The PMC(pollen mother cell) meiosis process and pollen morpholo(?)y of 4 species were observed and the pollen living activity of two species was measured. It was discovered that the PMC meiosis process of J. regia, J. mandshurica and J. nigra were basically normal, but that of J. hopeiensis was very irregular, i. e. univalenl, lagging chromosome, micronucleolus and polyspory. The karyotypes of 7 species were analysed. They are as follows: J. regia: 2n=2x=32=20m+10sm+2T; J. mandshurica: 2n=2x=32=22m+8sm+2T; J. hopeiensis: 2n=2x=32=18m+12sm+2T; J. cordiforrnis: 2n=2x=32=18m+12sm+2T; J. sieboldiana: 2n=2x=32=18m+12sm+2T; J. sigillata: 2n=2x=32=24m+6sm+2T; and J. nigra: 2n=2x=32=16m+12sm+2st+2sm(SAT).According to the karyotype and pollen characters, 7 species tested were divided into 3 sections, and they are sect. Juglans, sect Cardiocaryon and sect Rhysocaryon. The evolutionary relationships among the sections and the species in one section were approached. The author considered that J. hopeiensis should be regarded as an independence species and the Juglandaceae was probably derived from two different plants with x=8 in phylogeny, and supported the view that China should be one of the original places of J. regia.