This tiny delicate terrestrial orchid is confined to parts of the Australian east coast and is considered rare.
Introduction
Many familiar orchid species are exotic, colourful and flamboyant, but the family includes very numerous less conspicuous examples, rarely cultivated and best appreciated in their natural habitat. Sharp eyes and careful searching in the right place at the right time are needed to detect many of the smaller species of ground orchids, but discovering a new patch of a cryptic species and taking the time to examine its finer features can be especially rewarding.
Taxonomy
Formerly known as Acianthus amplexicaulis, the Green Midge Orchid is now placed in Acianthella, a genus with seven species, two of which are found in Australia. The group includes species with small green flowers, while most of those remaining in the genus Acianthus are more robust, with brown to red-purple flowers, along with other distinguishing floral characteristics.
Description
The Green Midge Orchid is a ground orchid, arising from a small underground tuber. A single leaf, heart-shaped but lobed, is held 1-2 cm above the ground, with a flowering stem up to 9 cm long with 2-20 flowers rising above the leaf. The flowers are up to 5 mm long and translucent green, with a distinctive apron-shaped labellum. Plantnet provides a detailed taxonomic description.
Range
The Green Midge Orchid is confined to south eastern Queensland and north eastern New South Wales, Australia.
Habitat
The Green Midge Orchid is found in moist environments on forest floors or in coastal scrubs, usually in groups of several to tens of individuals. While some references suggest that the species is found only close to the sea, its distribution is now understood to extend to near coastal ranges and tablelands.
Biology
The orchids are dormant underground through the dry and hot times of the year, commencing growth during summer and flowering in late summer through to early winter. Flowers self-pollinate, with rapid development of capsules splitting to shed tiny, wind-dispersed seeds. Seed germination is the only method of reproduction.
Conservation status
In 1996, J.D Briggs and J.H. Leigh (Rare or Threatened Australian Plants, CSIRO, Canberra) considered the Green Midge Orchid to be rare. The plants have been observed frequently over the last decade, and it is likely that the tiny specimens with their seasonal dormancy are often overlooked even by careful observers. Many forest habitats are depleted and threatened, however, so even if the Green Midge Orchid proves to be more common than currently recognised, active conservation of the species will be appropriate.
Further reading
Jones, D.L. and Clements, M.A., 2004. Acianthella. Orchadian 14(7): 331.
