Operculum development in Eucalyptus clöeziana and Eucalyptus informal subg. Monocalyptus (Myrtaceae)

Abstract

Flowers of Eucalyptus clöeziana have two clearly distinct perianth whorls. The small free parts of the outer (calycine) whorl cease growth early and are lost from the flower; the parts of the inner (corolline) whorl become continuous laterally by confluence of growth centres and form an operculum in the mature flower. The stamens are inserted on a circumfloral buttress (staminophore) that is homologous to the adaxial corolline component in Angophora and the bloodwood and Eudesmia eucalypts. Flowers of Monocalyptus have only one perianth whorl, which is opercular. The stamens are similarly inserted on a circumfloral buttress. Developmental study does not provide conclusive evidence for either..