Phenology of inflorescence development in pohutukawa (Metrosideros excelsa, Myrtaceae)

Abstract

The development of compound inflorescences in Metrosideros excelsa over a 10-week period is described. We identify six developmental key stages from dormancy to bud break according to morphological characteristics and present a time course of inflorescence development. Vegetative and compound inflorescence buds are initially morphologically identical, with several bud scales and a spheroidal shape (stage I). Allometric changes result in ellipsoidal buds for approximately eight days (stage II). Deciduous bracts subtending the secondary inflorescence axes partly cover cymose inflorescence buds at stage III. These bracts abscise by stage IV. A pair of bracts and two pairs of bracteoles, subtending lateral flower buds in each cymose inflorescence, become visible at stage V. After all bracts and bracteoles have abscised, individual flower buds appear clearly separated and petals become visible (stage VI).