In Australia, our mainland forests (excluding the relatively small areas of rainforest), are dominated by two genera of trees, Eucalyptus and Acacia. Many of the latter are commonly known as ‘wattles’ and very few people in Australia would not be familiar with the sight of a wattle in flower, they can be very eye-catching (and grace our national coat-of-arms). The flowers are mostly yellow, either single ‘pom-poms’ of fluffy stamens, or smaller individual flowers that form short racemes like mini sheep’s tails.
The name ‘black wattle’ was given by early colonists to an unrelated shrubby tree (Callicoma serratifolia), the long, supple branches of which they used to make their wattle and daub shelters. The name wattle subsequently migrated to the acacias, presumably due to the vaguely similar flowers, and is now the universal common name for the majority of acacias that haven’t retained indigenous or other descriptive common names.
Acacias have adapted to an even wider range of habitats than the eucalypts. This is in part due to the majority of species having dispensed with true leaves; instead they have evolved modified, leaf-like stems (called phyllodes) which better control water loss. The most obvious difference from ‘normal’ leaves is that the veins run parallel to the edges instead of branching off a central rib.
Seedlings start out with true compound leaves but by the time they are about 150mm high, they have begun to abandon these for the flattened stems which become the new
