Effect of Temperature and Grafting on Vegetative Growth Phases of Algerian Ivy

Abstract

THE closely similar English and Algerian ivies, Hedera helix, Linn, and Hedera canariensis, Willd., do not flower until the juvenile vining type of growth changes into a stiff erect form. This mature type of growth has entire, ovate to lanceloate leaves, and the round stems rarely produce aerial roots. The juvenile trailing stems are somewhat flattened, frequently produce aerial roots, and the leaves are palmately lobed. Both stems and petioles frequently have red pigments. Doorenbos¹ was able to produce many reversions to the juvenile form by grafting the mature fruiting form of English ivy on juvenile two- or three year seedlings or on juvenile plants grown from cuttings. Plants of adult ivies grown on juvenile understocks for approximately a year outdoors in a lath house in the relatively cool coastal climate of west Los Angeles did not exhibit the reversions described by Doorenbos. Preliminary experiments indicated that mature budded plants on juvenile understocks all reverted to the juvenile form when grown for more than a year at 80° F. but produced few reversions at lower temperatures.