Extrafloral Nectaries of Some Australian Bipinnate Acacias

Abstract

The extrafloral nectaries of some Australian bipinnate Acacia species are examined, coming from three sections: Acacia (two species); Botrycephalae (27 species); and Pulchellae (12 species). The nectaries are of the same three types as are found in phyllodineous species, i.e. porate (22 species of Botrycephalae), non-porate (three species of Botrycephalae, 11 of Pulchellae and one of Acacia) and flat (one species of Botrycephalae and one of Acacia). Two species, one of Botrycephalae and one of Pulchellae, are found to lack nectaries. Variations of the porate type, called porate-chambered, and the non-porate type, called non-porate-stipitate, are described. Relationships are shown between infrageneric taxa and nectary type and leaf axis length and nectary type, and evolutionary trends in nectary structure are discussed.