Lomandra longifolia (sagg) is a tufted tussock like plant.  Leaf blades are are smooth, flat to slightly concavo-convex, 30-100 cm in length and 4.5-8 mm wide. The leaf apex is irregular and 2-3 toothed and the leaf sheath edges are brown.

Branched inflorescences (10-35 cm in length) are held on scapes up to 35 cm in length.  Densely clustered flowers are in whorls around the nodes of the branches. Bracts at the base of flower clusters are usually longer than the flowers. Outer perianth is brown or purple, inner perianth is fleshy and white/cream in colour.

Grows in coastal dunes, scrub and heath, also under light forest cover from sea level to 750 m in altitude.