Aporostylis is a monotypic genus of terrestrial orchids in the family Orchidaceae, containing a single known species: Aporostylis bifolia, the odd-leaved orchid. The genus is endemic to New Zealand, where it occurs across the North Island (from Te Moehau southward), the South Island, Stewart Island/Rakiura, the Chatham Islands, the Antipodes Islands, the Auckland Islands, and Campbell Island.
Plants are stocky, glandular-hairy, perennial tuberous herbs that are spring to summer-green, growing up to 200 mm tall at flowering. The globose-conical tubers give rise to an erect stem densely covered in glandular hairs. A distinctive feature is the pair of broadly ovate-oblong leaves set close together near the base of the stem; the lower leaf reaches 100–200 mm in length, while the upper is usually noticeably shorter. Both leaves are dark green, frequently spotted brown or purple, and fringed with glandular hairs. Flowers are typically solitary and up to 250 mm in diameter, white or pink, and also glandular-pubescent. The labellum is sessile and broadly expanded, bearing two median rows of yellow calli near the base.
The genus name Aporostylis alludes to its "perplexing style" — a reference to the unusual column morphology that originally made taxonomic placement uncertain. The plant is most likely to be confused with Caladenia or Chiloglottis, from which it differs by its paired, spotted, broadly ovate leaves and glandular-hairy flowers with white or pink sepals and petals.
Aporostylis bifolia was assessed as Not Threatened under the New Zealand Threat Classification System in 2023.
Etymology
The genus name Aporostylis derives from Greek roots meaning "perplexing style," reflecting the unusual column structure that complicated early taxonomic placement. The species epithet bifolia comes from the Latin bis (two) and folium (leaf), describing the plant's characteristic paired leaves.
Distribution
Aporostylis bifolia is endemic to New Zealand, occurring on the North Island (from Te Moehau southward), the South Island, Stewart Island/Rakiura, the Chatham Islands, the Antipodes Islands, the Auckland Islands, and Campbell Island. The species ranges from subalpine and high-montane habitats in the north to lowland and coastal settings in the southern part of its range.
Ecology
Aporostylis bifolia grows in bogs, seepages, damp open ground, shrubland, tussock grassland, and both native and plantation forest — it is notably tolerant of pine forestry. It is classified as a facultative wetland plant (FACW), meaning it usually occurs in wetland habitats but can also be found in drier upland sites. Flowering takes place from October to March, with fruiting from December to May. The minute seeds are dispersed by wind.
Conservation
Aporostylis bifolia is assessed as Not Threatened nationally under the New Zealand Threat Classification System (2023), and Regionally Not Threatened in Otago (2025). The species is not commercially available and should not be removed from the wild.
Propagation
Propagation is considered difficult; the species should not be removed from the wild. No reliable cultivation technique has been documented.
