It has a single thick, fleshy, channelled leaf and up to fifteen pale blue flowers with an almost spherical yellow lobe on top of the anther.

The lobe on the top of the anther is light brown and gently curved with a yellow, almost spherical tip but with a deep notch.

[2][3] Thelymitra silena was first formally described in 1999 by David Jones from a specimen collected on Clarke Island and the description was published in The Orchadian.

[4] The specific epithet (silena) is derived from the Latin word meaning "a bearded, bald, woodland deity, similar to but older than a satyr",[5] referring to the column of this orchid.

[6] The madonna sun orchid usually grows in grassy forest and is found near the north and east coasts of Tasmania and on Clarke Island.