Shoot growth and heterophylly in ginko biloba

Abstract

Ginkgo biloba resembles other woody plants with long and short shoots in having variable leaves, and this variability in shape and other characteristics is closely related to the specialization of the shoots. The unlobed or bilobed early leaves of short shoots are preformed in the winter bud, and their nearly synchronous expansion in the spring is not accompanied by stem elongation. The leaves clustered at the base of long shoots are like short-shoot leaves in origin, time of appearance, and form, but they are succeeded by a second set of leaves whose internodes elongate. These multilobed late leaves develop at intervals of several days, and their production sometimes continues throughout the summer. The early and late leaves differ in the circumstances and continuity of ontogeny, and their differences in form originate at an early stage. The similarity of the late leaves to the deeply cut leaves of seedlings appears to be due to a common mode of ontogeny, rather than to any tendency to revert to a juvenile or ancestral state, as suggested in the past. The developmental events described here are strongly correlated with the pattern of auxin production found by earlier workers, and it is suggested that auxin is the principal hormonal intermediary between the production of a second set of leaves on long shoots and the elongation of those shoots.

Citation

Critchfield, William B. 1970. Shoot growth and heterophylly in ginko biloba. Bot. Gaz. 131(2): p. 150-162