Acacia

Most acacias have compound pinnate leaves. In some species, however, especially in the Australian and Pacific islands species, the leaflets are reduced, and the leaf-stalks (petioles) become vertically flattened phyllodes serving the purpose of leaves. A few species lack leaves or phyllodes altogether, but possess instead modified leaf-like photosynthetic stems functioning as leaves. Many species bear spines (modified stipules), especially those species growing in arid regions. Inflorescence is a cylindric spike, globose head or panicle, solitary or in clusters, axillary or at the end of branches. The small flowers are 3-5-merous, with conspicuously long stamens, yellow or cream-colored in most species, whitish in some, even purple or red. Petals are usually more or less united, rarely absent. Calyx is campanulate, dentate, lobed or sepals are free. Stamens are numerous (more than 10), free or shortly and irregularly connate at the base. Fruit (legume) is ovate to linear, straight, arcuate or contorted, membranous to woody, rarely jointed or moniliform (resembling a string of beads). Seed is large, with a filiform funicle or fleshy aril.