Acronychia crassipetala, commonly known as crater aspen, is a species of flowering plant in the citrus family, Rutaceae. This evergreen tree is native to eastern Australia, where it plays a role in its natural ecosystems. The growth habit of Acronychia crassipetala is that of a medium to large tree, typically reaching heights of 10 to 25 meters, though occasionally taller specimens are found. Its trunk is usually straight and can develop a diameter of up to 60 centimeters. The bark is generally smooth and greyish, becoming slightly rougher with age. The leaves are arranged oppositely along the stem and are compound, usually trifoliate, meaning each leaf stalk bears three leaflets. The leaflets are ovate to elliptic in shape, with entire or slightly crenulate margins, and possess a glossy, dark green upper surface and a paler, often glaucous, underside. A distinctive feature of the leaves is the presence of translucent oil dots, which are visible when the leaf is held up to the light and are characteristic of many Rutaceae species. Flowering occurs from late spring through summer, producing clusters of fragrant flowers. The flowers are typically white or cream-colored and possess four petals. The petals are fleshy and somewhat thickened, a characteristic reflected in the specific epithet "crassipetala," meaning "thick-petaled." The fruit is a drupe, which matures into a fleshy, globose to ovoid structure, often with a distinct crater-like depression at the apex, hence the common name "crater aspen." The fruit is typically pale green to yellowish when ripe and contains one or two seeds. Acronychia crassipetala is found in rainforests and wet sclerophyll forests, often growing along creek banks or in moist gullies. Its natural distribution extends along the coastal regions of New South Wales and Queensland. While it thrives in these humid, sheltered environments, it can also adapt to cultivation in well-drained soils and a range of light conditions, from full sun to partial shade, provided it receives adequate moisture. It is considered a hardy and relatively low-maintenance tree once established. Ecologically, the fruits of Acronychia crassipetala are a food source for various native birds and mammals. The plant's presence contributes to the biodiversity of its native habitat. While not widely cultivated for ornamental purposes, its attractive foliage, fragrant flowers, and interesting fruit make it a desirable addition to native gardens and revegetation projects. There is limited documented use of this species for medicinal, culinary, or economic purposes, with its primary significance lying in its ecological role and potential as a horticultural subject for enthusiasts of Australian native flora. The translucent oil dots in the leaves are a key identification feature, releasing a characteristic citrus-like scent when crushed.