Pterostylis revoluta, commonly known as the autumn greenhood, is a species of orchid endemic to south-eastern Australia. As with similar greenhoods, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves flat on the ground but the flowering plants have a single flower with leaves on the flowering spike. This greenhood has white and green flowers that have a long, curved, pointed labellum which extends beyond the sinus between the lateral sepals.
Pterostylis revoluta is a terrestrial, perennial, deciduous, herb with an underground tuber and when not flowering, a rosette of between three and seven greyish to bluish, egg-shaped leaves. Each leaf in the rosette is long and wide. Flowering plants have a single flower long, wide and that lean forwards slightly. The flower is borne on a flowering stem high with between three and five leaves wrapped around the stem. The flowers are pale green and white with a brown tinge. The dorsal sepal and petals are fused, forming a hood or "galea" over the column. The dorsal sepal curves forward and downward with a thread-like tip long. The lateral sepals are held closely against the galea, have an erect, curved thread-like tip long and a narrow V-shaped sinus between their bases. The labellum is long, about wide, curved, pointed and extends for about half its length above the sinus. Flowering occurs from February to June.[1] [2]
Pterostylis revoluta was first formally described in 1810 by Robert Brown and the description was published in the Prodromus Florae Novae Hollandiae et Insulae Van Diemen.[3] [4] The specific epithet (revoluta) is a Latin word meaning "turned over" or "rolled back".[5]
The autumn greenhood grows on sheltered slopes in forest and in coastal scrub in coastal and near-coastal area from south-east Queensland to Nowra in New South Wales and as far inland as Cessnock.