Lomandra banksii, commonly known as tropical mat rush, is a species of plant in the asparagus family Asparagaceae. It is native to New Guinea, New Caledonia and the state of Queensland, Australia.
Lomandra banksii is a shrub up to tall, beginning to flower when about one metre tall. Leaves are long and narrow, up to long by wide, arranged in tight whorls around the stem. They have numerous longitudinal veins and very fine serrations on the edges; the leaf tip is blunt with one to three indistinct teeth. The leaves separate from the stem close to the leaf base, and the base remains attached to the stem for some time.
The inflorescence is and about long, with successive whorls of flower-carrying branches more than apart. This species is dioecious, meaning that (functionally female) and (functionally male) flowers are borne on separate plants. All flowers are (without a stem) and have six tepals in two whorls of three; male tepals measure up to long and female tepals are up to long.
The fruit is a capsule about long by wide, with the tepals remaining attached at the base and a sharp point at the apex. They have three segments, each containing a single seed coated in a red aril.
This species is listed as least concern under the Queensland Government's Nature Conservation Act. , it has not been assessed by the International Union for Conservation of Nature (IUCN).