Preformation of node number in vegetative and reproductive proleptic shoot modules of Persea (Lauraceae)

The numbers of nodes on single flush terminal and axillary shoot modules were determined in a range of Persea species and cultivars. They were compared with node numbers in apical and axillary buds to investigate whether preformation or neoformation of nodes occurred. Mean number of nodes on terminal shoots was 14 for vegetative shoot modules and 21 for reproductive shoot modules, and was similar across species, cultivars, rootstocks, locations and climates. In the cultivar 'Hass', numbers of nodes on axillary shoot modules were variable, and lower than those for primary shoot modules forming the dominant growth axis of annual growth modules. There was a mean of 12 nodes for vegetative proleptic shoot modules, 15 for reproductive proleptic shoot modules and six for sylleptic shoot modules, which were invariably vegetative. All nodes were preformed within both apical and axillary proleptic buds. This was not the case in sylleptic buds, which burst contemporaneously with extension of the parent axis. The majority (63percent)of reproductive buds formed indeterminate compound inflorescences. They carried six basal bud scales, six axillary inflorescences and their subtending bracts, and up to nine true leaves.