Seedling morphology and classification in the Bisectae group of Eucalypts

Abstract

A few species of Eucalyptus produce heath-like seedlings in which the leaves are developed in spirals or are densely clustered, unlike seedlings of most eucalypts which have a decussate phyllotaxis. Heath-like seedlings were found to be characteristic of Eucalyptus oleosa F. Muell. ex Miq., E. oleosa var. obtusa C. A. Gardner, E. longicornis F. Muell., E. brockwayi C. A. Gardner, and E. formanii C. A. Gardner. Low percentages of heath-like seedlings were found among the progeny of E. foecunda Schau., E. calycogona Turcz., E. gracilis F. Muell., and E. socialis F. Muell. ex Miq. All heath-like seedlings examined were of species belonging to Maiden's "division" Bisectae but belong to groups of species widely separated on anther characters in Blakely's classification. The significance of eucalypt seedling morphology is discussed in relation to classification within the Bisectae group.