Secondary Pollen Presentation in the Chamelaucium Alliance of the Myrtaceae: a Compact Substigmatic Ring in Chamelaucium

Abstract

In Chamelaucium uncinatum (Geraldton wax), the flowers are protandrous and pollen is presented to potential pollinators on a compact ring of stylar hairs. The anthers dehisce in the bud, and the pollen which is suspended in a lipidic fluid adheres to the stylar hairs as the stamens uncurl. The style elongates after anthesis to present the stigma and pollen. The period of stigmatic receptivity and pollen viability and the developmental changes in the flower are described. The stylar hairs present the pollen, then remove it from the vicinity of the stigma prior to the period of stigmatic receptivity. The methods of pollen presentation in other species of Chamelaucium are also investigated. Stylar elongation is compared in long- and short-styled species of Chamelaucium, Darwinia, Homoranthus and Actinodium. The previous accounts of the breeding system of C. uncinatum are discussed.