Claim: Diuris arenaria is a tuberous herb with up to nine mauve flowers, and the sepal is more or less erect.
Evidence: Diuris arenaria is a tuberous, perennial herb with two linear to lance-shaped leaves 150–500 mm (6–20 in) long, 2–6 mm (0.08–0.2 in) wide and folded lengthwise. Up to nine mauve or light purple and white flowers 20–30 mm (0.8–1 in) wide are borne on a flowering stem 150–500 mm (6–20 in) tall. The sepal is more or less erect, egg-shaped, 10–18 mm (0.4–0.7 in) long and 7–11 mm (0.3–0.4 in) wide.