With no major mountain ranges or rivers to prevent their spread, the wattles began to spread all over the continent as it dried and fires became more common. They began to form dry, open forests with species of the genera Allocasuarina, Eucalyptus and Callitris (cypress-pines). The southernmost species in the genus are Acacia dealbata (silver wattle), Acacia longifolia (coast wattle or Sydney golden wattle), Acacia mearnsii (black wattle), and Acacia melanoxylon (blackwood), reaching 43°30' S in Tasmania, Australia. Fossil record An Acacia-like long fossil seed pod has been described from the Eocene of the Paris Basin. Acacia-like fossil pods under the name Leguminocarpon are known from late Oligocene deposits at different sites in Hungary. Seed pod fossils of †Acacia parschlugiana and †Acacia cyclosperma are known from Tertiary deposits in Switzerland. †Acacia colchica has been described from the Miocene of West Georgia. Pliocene fossil pollen of an Acacia sp. has been described from West Georgia (including Abkhazia). Oldest records of fossil Acacia pollen in Australia are from the late Oligocene epoch, 25 million years ago. Distribution and habitat They are present in all terrestrial habitats, including alpine settings, rainforests, woodlands, grasslands, coastal dunes and deserts. In drier woodlands or forests they are an important component of the understory. Elsewhere they may be dominant, as in the Brigalow Belt, Myall woodlands and the eremaean Mulga woodlands. In Australia, Acacia forest is the second most common forest type after eucalypt forest, covering or 8% of total forest area. Acacia is also the nation's largest genus of flowering plants with almost 1,000 species found. Ecology Acacia is a common food source and host plant for butterflies of the genus Jalmenus. The imperial hairstreak, Jalmenus evagoras, feeds on at least 25 acacia species. Many reptiles feed on the sap, such as the native house gecko in Australia. The sap is also consumed by bugs (Hemiptera), such as Hackerobrachys viridiventris and Sextius virescens. Toxicity Some species of acacia contain psychoactive alkaloids, and some contain potassium fluoroacetate, a rodent poison. Uses The seed pods, flowers, and young leaves are generally edible either raw or cooked. Aboriginal Australians have traditionally harvested the seeds of some species, to be ground into flour and eaten as a paste or baked into a cake. The seeds contain as much as 25% more protein than common cereals, and they store well for long periods due to the hard seed coats. In addition