Comparative Morphology and Anatomy of Axillary Buds Along a Rose Shoot

The lateral buds of rose plants were separated into three groups according to position in the axils of different leaves along the shoot. (1) Buds in the axils of the uppermost leaves with one or three leaflets beneath the terminal flower are sylleptic; i.e., they grow continuously from their initiation without periods of inhibition. (2) Buds in the axils of the lower leaves with five leaflets and in the axils of the lowest bractlike leaves are proleptic; they undergo a period of inhibition at a very early stage, thus developing fewer primordia and a small amount of parenchyma cells in the pith. (3) Buds located between 1 and 2, in the axils of seven-leaflet leaves and upper five-leaflet leaves, are also proleptic, but leaf primordia continue to form during "inhibition." Buds in the axils of upper and lower five-leaflet leaves have the same growth potential; however, there was a 1-wk growth delay of the lower buds, indicating a stronger inhibition state in the bud. The leaves of the lower half of the shoot were present as primordia in the "mother bud," which produced the shoot. This section contained the inhibited proleptic buds, suggesting that the lower axillary buds were influenced, on formation, by the physiological conditions prevailing in the leaf primordia axils before the bud sprouted.