Chromosome Numbers and the Anatomy of the Secondary Xylem in the Oleaceae

With two text figures Tue OLEACEAE form a natural family of plants, although there are well marked differences between most of the genera.The family is divided into the Oleoideae which includes Frazinus, Forsythia, Syringa, Forestiera, Chionanthus, Olea, and Ligustrum, and the subfamily Jasminoideae which includes Jasminum. According toRehder there are more than 20 genera with over 400 species, most of which are trees and shrubs.The natural grouping of these genera is indicated not only by their taxonomic characters but also by their immunological, grafting, and anatomical relationships.Chester (1931) working with Chionanthus, Fraxinus, Forsythia, Ligustrum and Syringa, found no normal precipitin reactions between these genera.According to DeCandolle the Lilac can be grafted on Ash, Chionanthus and Fontanesia while the Persian Lilac grafted on Phillyrea survived for ten years.The Olive can also be grafted on Phillyrea and Frazinus.Syringa is commonly grafted on Ligustrum stock, although as Chester has pointed out, this practice often leads to "graft blight" due to incompatibility between stock and scion.The writer has seen Syringa grafts on Frarinus which made 1932