A tufted, perennial herb. Grass-like appearance. Dioecious.

"Leaves flat or slightly concavo-convex, occasionally rolled, usually 50-100 cm long and 4.5-7.5 mm wide, glabrous; apex 2- or 3-toothed, central tooth in pronounced sinus or longer than laterals;..." (Flora of Australia)

Lomandra longifolia transplants are produced in considerable quantities by nurseries. The seed is utilised in coastal and some inland rehabilitation works. Considerable quantities of seed can be procured in optimum natural settings which are usually seasonal watercourses or flats with relatively high penetration of sunlight. This may include tall open eucalypt forest or woodland settings besides cleared areas. Years with higher Spring rainfalls produce seed in central to southern Queensland which ripens around late December or early January.

L. longifolia may be confused with Lomandra confertifolia subsp. pallida and with Lomandra hystrix. The teeth at the tips of the leaves will separate L. longifolia from L. hystrix. In our areas of observation, we generally find L. hystrix along creek beds and rivers which maintain flows for large parts of the year. L. longifolia will occur the same way however it will also colonise much drier sites, often along banks some distance from regular water, along dry gullies and washouts, up onto hillsides and also on to ridges. As the sites become drier, the frequency of plants and their size may decrease.

Flora of Australia. Australian Biological Resources Study, Canberra. [Date Accessed: Nov 13, 2019] http://www.ausflora.org.au https://profiles.ala.org.au/opus/foa/profile/Lomandra%20longifolia