Pterostylis dolichochila, commonly known as the long-tongued shell orchid, is a species of orchid endemic to southern Australia. As with similar orchids, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves but the flowering plants have a single flower with leaves on the flowering spike. This greenhood has a green and white flower with reddish-brown stripes and a sharply pointed sepal.
Pterostylis dolichochila is a terrestrial, perennial, deciduous, herb with an underground tuber and when not flowering, a rosette of four to ten egg-shaped leaves. Each leaf is 4âÂÂ12 mm long and 3âÂÂ8 mm wide. Flowering plants have a single flower 20âÂÂ25 mm long and 7âÂÂ9 mm wide borne on a spike 50âÂÂ150 mm high with three or four stem leaves wrapped around it. The flowers are green and white with reddish-brown stripes. The dorsal sepal and petals are fused, forming a hood or "galea" over the column. The dorsal sepal curves forward with sharp point or a thread-like tip 1âÂÂ2 mm long. The sepals are held closely against the galea, have an erect, thread-like tip 15âÂÂ20 mm long and a broad, flat sinus between their bases. The labellum is 13âÂÂ15 mm long, about 4 mm wide, brown, blunt, and curved and protrudes above the sinus. Flowering occurs from April to August.
Pterostylis dolichochila was first formally described in 1985 by David Jones and Mark Clements and the description was published in the fourth edition of Flora of South Australia. The specific epithet (dolichochila) is derived from the Ancient Greek words dolichos meaning "long" and cheilos meaning "lip".
The long-tongued shell orchid grows on calcareous sand and limestone, sometimes forming large colonies, in mallee in the south-east of South Australia and the Little Desert and Big Desert areas of Victoria.