structures, rejuvenate or scour channels, and increase hydraulic capacity to reduce flooding. However, the Murray–Darling Basin Commission has recognised the importance of snags as aquatic habitat, and a moratorium on their removal from the Murray River has been recommended. Hollows start to form at around 120–180 years of age, creating habitat for many wildlife species, including a range of breeding and roosting animals such as bats, carpet pythons, and birds. The dense foliage of the tree also provides shade and shelter from the sun in drier areas. The superb parrot, a threatened species, is amongst the bird species that nest in the river red gum. River red gums contribute to the provision of nutrients and energy for other species through leaf and insect fall. This is especially important to the ecology in areas of low nutrients. The tree's preferred habitat of floodplains and watercourses also gives it the role of flood mitigator, which slows silt runoff. Weed The global weed compendium lists E. camaldulensis as a weed in Portugal, Canary Islands, South Africa, Spain, Bangladesh, the United States, Ecuador, the Galapagos and other countries. The species, while native to parts of Western Australia, has become naturalised via garden escapees and introduction as a restoration plant; they are the subject of weed management programs. Its ability to tolerate drought and soil salinity, together with its prolific seed production, and capacity to reproduce when very young, mean that it is highly adaptable, and it has been declared invasive in South Africa, California, Jamaica, Spain, and Hawaii Reproduction and dispersion The flower begins as an "invaginated receptacle". The operculum, or cap, protects the interior of the flower bud, as the male and female parts develop. The male parts of the flower consist of the stamen, a slender filament, and the anther, two pollen sacs located at the top of the stamen. The anther sacs open into longitudinal slits to release their pollen. These filaments will extend to encircle the receptacle during flowering. The female parts of the flower, the ovaries, are contained in ovary chambers. These chambers are separated from the receptacle containing the male parts by a disc. From the top of the ovaries a structure called the style extends into the receptacle, to form the stigma. During flowering, pollen from the anthers can fall onto the stigma. This can occasionally lead to self-pollination, although the stigma does not become receptive until