It is similar to T. ixioides but has fewer, smaller flowers with larger dark blue spots.Thelymitra juncifolia is a tuberous, perennial herb with a single channelled, dark green thread-like to lance-shaped leaf 150–200 mm (6–8 in) long and 8–10 mm (0.3–0.4 in) wide.

The lobe on the top of the anther is short, yellow or orange with a red or dark purple band on the back and several rows of crowded, finger-like glands.

The side lobes have relatively sparse, mop-like tufts of white or bluish hairs.

[2][3] Thelymitra juncifolia was first formally described in 1840 by John Lindley and the description was published in his book The Genera and Species of Orchidaceous Plants.

[6]: 466 The large-spotted sun orchid is widespread and common in Australia within its range.