Flowering stem erect, wiry, straight, 7–10 cm tall, c. 1 mm diam., green to purplish. Leaf filiform, terete, 3–5 cm long, 1–2 mm wide, obscurely canaliculate, sheathing at base, green with a purplish base. Inflorescence 1(–2)-flowered. Sterile bracts 2. Perianth segments lanceolate to ovate, 5–7 mm long, deep blue with reddish tones. Column slender, 3–4 mm long, purplish, mid-lobe expanded into hood over the anther, tubular, inflated, narrow at the base, widening abruptly towards the apex, curved, purplish brown, with little or no hoary bloom, apex deeply v-notched, yellow; lateral lobes converging or more or less parallel, 1–2 mm long, digitiform or laterally compressed, porrect or obliquely erect, each with a sparse shaggy toothbrush-like arrangement of cream or yellow hairs embracing the mid-lobe. Anther inserted towards middle of column, shortly beaked. Flowers Oct.–Nov.
Flowers are self-pollinating and only open on warm, humid days.
Thelymitra orientalis is similar to T. mucida, but the latter is a generally more robust plant with a larger leaf, up to 6 flowers and copious bloom on the mid-lobe of the column.
