About Thelymitra arenaria Lindl.
Thelymitra arenaria is a tuberous, perennial herb. It produces a single leathery, channelled leaf that is dark green and linear to lance-shaped. The leaf measures 150–300 mm (6–10 in) long, 8–18 mm (0.3–0.7 in) wide, and has a purplish base. Between two and sixteen purplish flowers, each 16–26 mm (0.6–1 in) wide, grow on a flowering stem 240–400 mm (9–20 in) tall. There are usually two bracts on the flowering stem. The sepals and petals are 8–15 mm (0.3–0.6 in) long and 4–8 mm (0.2–0.3 in) wide. The structure at the center of the flower called the column is pale blue with dark blue streaks, 4.5–6 mm (0.18–0.24 in) long and 2.5–3.5 mm (0.098–0.14 in) wide. The lobe on the top of the anther is dark brown with a yellow tip and gently curved. The side lobes curve upwards and have dense, hairbrush-like tufts of white hairs. The flowers are self-pollinating and only open on warm to hot, humid days. Flowering occurs from October to December. This species is commonly called the forest sun orchid. It is widespread and common across most of its range. It grows in a wide range of habitats from grassland to forest, and is found in southern New South Wales, the Australian Capital Territory, the southern half of Victoria, south-eastern South Australia, and Tasmania.
