Pterostylis aphylla

Pterostylis aphylla, commonly known as the leafless greenhood, is a species of orchid endemic to Tasmania. 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 in this species, the flowering plants have a single green and white flower with a brown tip and lack leaves apart from a few small scales.

Leafless greenhood
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Cranichideae
Genus: Pterostylis
Species:
P. aphylla
Binomial name
Pterostylis aphylla

Description

Pterostylis aphylla is a terrestrial, perennial, deciduous, herb with an underground tuber. Non-flowering plants have a rosette of dark green leaves 4–10 mm (0.2–0.4 in) long and 3–8 mm (0.1–0.3 in) wide. Flowering plants have up to five moderately crowded green and white flowers with a dark brown tip, on a flowering spike, 70–150 mm (3–6 in). The dorsal sepal and petals are fused, forming a hood or "galea" over the column. The dorsal sepal is erect near its base, then curves forward with a short point. The lateral sepals are erect, held closely against the galea with thread-like tips about 3 mm (0.1 in) long that do not project above the galea. The sinus between the bases of the lateral sepals curves inward and has a small notch in the centre. The labellum is about 3 mm (0.1 in) long, 71 mm (3 in) wide, dark brown and not visible outside the intact flower. Flowering occurs from October to March.[2]

Taxonomy and naming

Pterostylis aphylla was first formally described in 1840 by John Lindley from a specimen collected in the north-east of Tasmania and the description was published in The Genera and Species of Orchidaceous Plants.[1][3]

Distribution and habitat

The leafless greenhood is widespread in Tasmania where it grows in forest, heath and buttongrass moorland.[2][4]

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References
  1. "Pterostylis aphylla". APNI. Retrieved 14 June 2017.
  2. Jones, David L. (2006). A complete guide to native orchids of Australia including the island territories. Frenchs Forest, N.S.W.: New Holland. p. 310. ISBN 978-1877069123.
  3. Lindley, John (1840). The Genera and Species of Orchidaceous Plants. London: Ridgways. p. 392. Retrieved 14 June 2017.
  4. Jones, David L. (1998). "Contributions to Tasmanian Orchidology". Australian Orchid Research. 3: 139.
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