兰屿百脉根（学名：Lotus australis）为豆科百脉根属下的一个种。

Lotus australis, known by its common name of austral trefoil, is a small, spreading herb from the family of Fabaceae. It normally grows to around 30-50 cm in height and is native to Australia.

Leaves are of a trifoliate shape and are small, with a light green colour. During spring, the plant bursts into beautiful massed displays of white pea flowers. In summer, these are replaced with stiff, tubular beans, which explode when they dry, releasing multiple small, black legume seeds. Austral trefoil is easily propagated from these seeds, by soaking the seeds in hot water overnight before sowing. This mimics the heat of a bushfire, which is a contributing factor in germination in the wild.