Acianthus
Encyclopedia
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, 8 endemic in Australia and 1 in New Zealand, from the orchid family (Orchidaceae
Orchidaceae
The Orchidaceae, commonly referred to as the orchid family, is a morphologically diverse and widespread family of monocots in the order Asparagales. Along with the Asteraceae, it is one of the two largest families of flowering plants, with between 21,950 and 26,049 currently accepted species,...
). Previously there were more species included in Acianthus, but about half of them have now been redistributed to other genuses, such as Acianthella
Acianthella
Acianthella is a small genus of tropical ground orchids previously included in Acianthus but is now distinguished "by tiny green flowers on long thin ovaries, sepals of similar shape and size, lacking apical clubs, narrow petals and no basal glands on the labellum." There are about 7 species...
.
The name is derived from the Greek words achis (point) and anthos (flower), referring to the pointed sepals. Common Australian names include "Pixie-caps," "Gnat Orchid," and "Mosquito Orchid." Acianthus species occur in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, in small groups in forests on decaying litter, or occasionally on partially decayed logs or in association with bracken
Bracken
Bracken are several species of large, coarse ferns of the genus Pteridium. Ferns are vascular plants that have alternating generations, large plants that produce spores and small plants that produce sex cells . Brackens are in the family Dennstaedtiaceae, which are noted for their large, highly...
fern.
These terrestrial
Terrestrial plant
A terrestrial plant is one that grows on land. Other types of plants are aquatic , epiphytic , lithophytes and aerial ....
orchids have small, globular, subterranean tubers from which the flower stems arise. They form dense vegetative colonies, in sheltered forest or heathland, and are often found underneath shrubs and bracken. There is a single, heart-shaped, clasping leaf
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
, often with purple markings, near the base, held horizontally above the soil. The flowers often resemble mosquitoes. These orchids produce a terminal raceme
Raceme
A raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...
, arising from near the center of a solitary leaf, bearing pinkish or greenish flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s with a long spur. There are small flowers (4 to 5 mm), blending in with the surroundings. They are pollinated by small gnats seeking the nectar from the unlobed labellum
Labellum
Labellum is the Latin diminutive of labium, meaning lip. These are anatomical terms used descriptively in biology, for example in Entomology and botany.-Botany:...
.
Species
- Acianthus amplexicaulis (NE. Queensland to EC. New South Wales, New Caledonia) - now classified as Acianthella amplexicaulis.
- Acianthus apprimus Early Mosquito Orchid (NSW Blue Mountains to New England highlands).
- Acianthus borealis Northern Mosquito Orchid (Qld. Mt. Windsor Tableland to Blackdown Tableland).
- Acianthus caudatus Mayfly orchid, dead-horse orchid (SE. Australia) - now classified as Nemacianthus caudatus.
- Acianthus collinus Inland Mosquito Orchid (NSW slopes of Great Darling Range between Taree and Crowther; ACT Black Mountains).
- Acianthus exiguus Tiny Mosquito Orchid (NSW Repton to Wardell).
- Acianthus exsertus Gnat orchid (E. & SE. Australia). (type species).
- Acianthus fornicatusAcianthus fornicatusAcianthus fornicatus, known as Pixie Caps is a small terrestrial orchid, found in Australia. A common ground plant growing in moist forests and coastal scrub. Found north of Eden, New South Wales. It flowers in winter with a red central stripe....
Pixie-caps (E. Australia). - Acianthus huegelii - now classified as Cyrtostylis huegeliiCyrtostylis huegeliiCyrtostylis huegelii is a perennial and herbaceous flowering plant, an orchid, found in Southwest Australia. It has also been named as the Midge Orchid, after a small flying insect found in the same region....
. - Acianthus ledwardii Ledward's Mosquito Orchid (SE. Queensland)(Extinct).
- Acianthus pusillus Small Mosquito Orchid (Qld. n. to Eungella, NSW, Victoria, Tasmania).
- Acianthus reniformis - now classified as Cyrtostylis reniformisCyrtostylis reniformisCyrtostylis reniformis, commonly known as Small Gnat-orchid, is a species of orchid from Australia....
. - Acianthus sinclairii (New Zealand - incl. Stewart I.), Chatman Is., Kermadec Is.)
- Acianthus sublestus (NE Queensland) - now classified as Acianthella sublestaAcianthella sublestaAcianthella sublesta is a member of the Acianthella , which is a small genus of tropical ground orchids previously included in Acianthus but distinguished "by tiny green flowers on long thin ovaries, sepals of similar shape and size, lacking apical clubs, narrow petals and no basal glands on the...
- Acianthus tenuissima - now classified as Cyrtostylis tenuissima.