Chromosome number and relationship in the Magnoliales

With plate 80 and four text fujurcs Magnol offer a suggestive group for cytological investigation.It is the purpose of the present paper to report the results of a cytological survey of several members of the Magnoliales with a discussion of the bearing of these results on taxonomic and phylogenetic relationships. 1The Magnoliales, according to Hutchinson (1921), may be separated into the following families: Magnoliaceae, Winteraceae, Schisandraceae, Himantandraceae, Lactoridaceae, Trochodendraceae, and Cercidiphyllaceae.In the collections of the Arnold Arboretum members of the Magnoliaceae, Schisandraceae, Trochodendraceae, #nd Cercidiphyllaceae are available for study.Through the cooperation of the Royal Botanic Garden, Kew, and the John Innes Horticultural Institution, Merton, England, it has been possible to extend the range of the investigation to include all the families in the order, with the exception of representatives of the Himantandraceae and Lactoridaceae.Table I gives the chromosome number of the species studied.The observations on the meiotic divisions were made from aceto-carmine and permanent smear preparations of pollen mother cells.The acetocarmine preparations were found to be superior for the study of chromosome number and chiasma frequency.The counts of Illicium floridanum and Drimys Winter! thod ing with aceto-carmine.The remaining somatic counts were secured from root tips by use of the usual permanent preparations of sectioned material.'The work reported in the present paper has been furthered through the cooperation of a number of investigators at this and other institutions.Thanks are due to the officials of the Royal Botanic Garden, Kew, and of the John Innes Horticultural Institution, especially to W. J. C. Lawrence, Curator, and Mr. L. La Cour of the latter institution, who provided the material of Trochodendron aralioides, Illicium religiosum, Tetracentron sinense, and Kadsura japonica.Professor I. W. Bailey of the Arnold Arboretum has kindly furnished the data regarding the anatomy of the group studied.Professor Karl Sax of the Arnold Arboretum suggested the investigation and has very generously provided the drawings and information regarding Cercidiphyllnm and Euptelea.