Acianthus exiguus

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Tiny mosquito orchid
Acianthus exiguus.jpg
Acianthus exiguus near Repton
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Diurideae
Genus: Acianthus
Species:
A. exiguus
Binomial name
Acianthus exiguus
Leaf Acianthus exiguus leaf.jpg
Leaf

Acianthus exiguus, commonly known as tiny mosquito orchid, [2] is a flowering plant in the orchid family Orchidaceae and is endemic to New South Wales in Australia. It is a terrestrial herb with a single, heart-shaped leaf and up to five translucent greenish-white flowers with pinkish markings and is found growing in forests on the north coast of the state.

Contents

Description

Acianthus exiguus is a terrestrial, perennial, deciduous, sympodial herb with a single heart-shaped, glabrous, dark green leaf which is light reddish-purple on its lower surface. The leaf is 18–30 mm (0.7–1 in) long, 15–20 mm (0.6–0.8 in) wide on a stalk 2–5 cm (0.8–2 in) high. [2] [3] [4] [5]

There are up to five flowers well-spaced on a thin raceme 6–10 cm (2–4 in) tall, each flower 5–7 mm (0.2–0.3 in) long. The dorsal sepal is oval to elliptic in shape, 4–5 mm (0.2–0.2 in) long, 3–3.5 mm (0.12–0.14 in) wide, translucent greenish-white with faint red markings and forms a hood over the column. The central vein extends about 1.5 mm (0.06 in) beyond the end of the labellum. The lateral sepals are 6–7 mm (0.2–0.3 in) long, about 0.7 mm (0.03 in) wide, linear to lance-shaped, often have a curved tip, are similar in colour to the dorsal sepal and project forwards below the labellum. The petals are a similar colour and are about 2.0–2.5 mm (0.08–0.1 in) long, narrow egg-shaped to lance-shaped and usually spread widely. The labellum is pink to pinkish-mauve, 3.5–4.0 mm (0.14–0.16 in) wide, about 2 mm (0.08 in) wide, with the edges not rolled and lacking teeth. The thick, fleshy callus covering most of the central area is green and has many small pimple-like papillae on the outer half. Flowering occurs from May to June. [2] [3] [4] [5]

This species is distinguished from other mosquito orchids by its small, greenish, semi-erect flowers and narrow, purplish labellum. [3] [4]

Taxonomy and naming

Acianthus exiguus was first formally described by David Jones in 1991 and the description was published in Australian Orchid Research from specimens found near Wardell. [6] [3] The specific epithet (exiguus) is a Latin word meaning "small", "little" or "petty". [3] [7] In a 1995 paper published in the journal Allertonia, Paul Kores claimed that A. exiguus and 3 other species are not distinct from A. fornicatus and should be regarded as a synonyms. [8] That position has been adopted by Plants of the World Online. [9]

Ecology

The flowers of this species, unlike those of other mosquito orchids, are self-pollinating. [10]

Distribution and habitat

This orchid grows in localised populations between Repton and Wardell in the North Coast region of New South Wales. [3] It grows in sandy soil and clay loam in tall, moist forest and rainforest. [2] [3] [4] [5]

Conservation

Acianthus exiguus has a ROTAP rating of 3RC-, indicating that it is uncommon. [5]

Related Research Articles

<i>Acianthus</i> Genus of flowering plants

Acianthus, commonly known as mosquito orchids, is a genus of about twelve species of plants in the orchid family, Orchidaceae. Mosquito orchids are terrestrial herbs with a single, heart-shaped, usually ground-hugging leaf and one to many small, green, pinkish or purplish flowers on a fleshy stalk. They are found in New Caledonia, Australia and New Zealand.

<i>Acianthus fornicatus</i> Species of flowering plant

Acianthus fornicatus, commonly known as bristly mosquito orchid or pixie caps, is a species of flowering plant in the orchid family Orchidaceae and is endemic to eastern Australia. It is a terrestrial herb with a single, heart-shaped leaf and up to ten translucent pinkish-red flowers, and is widespread and common in coastal and near-coastal areas.

<i>Acianthus apprimus</i> Species of flowering plant

Acianthus apprimus, commonly known as early mosquito orchid, is a species of flowering plant in the orchid family Orchidaceae and is endemic to New South Wales in Australia. It is a terrestrial herb with a single, heart-shaped leaf and between two and nine translucent pinkish flowers with reddish markings and is found in disjunct populations around the state.

Acianthus borealis, commonly known as northern mosquito orchid, is a species of flowering plant in the orchid family Orchidaceae and is endemic to Queensland in Australia. It is a glabrous, terrestrial herb with a single, heart-shaped leaf and between two and twenty transparent pinkish flowers with reddish markings and is widely distributed on the eastern tablelands.

<i>Acianthus collinus</i> Species of flowering plant

Acianthus collinus, commonly known as hooded mosquito orchid or inland mosquito orchid, is a species of flowering plant in the orchid family Orchidaceae and is endemic to south-eastern continental Australia. It is a terrestrial herb with a single, heart-shaped leaf and between two and nine translucent pinkish flowers with reddish markings and is found growing in colonies on sheltered slopes in open forest in on the western slopes of the Great Dividing Range.

<i>Acianthus exsertus</i> Species of flowering plant

Acianthus exsertus, commonly known as gnat orchid or large mosquito orchid, is a species of flowering plant in the orchid family Orchidaceae and is endemic to eastern Australia. It is a terrestrial herb with a single, heart-shaped leaf and up to 25 small, fine, dark brown flowers with pinkish and purplish markings and is found growing in sheltered places in forests in Queensland, New South Wales the ACT and Victoria.

<i>Acianthus pusillus</i> Species of flowering plant

Acianthus pusillus, commonly known as small mosquito orchid, is a species of flowering plant in the orchid family Orchidaceae and is endemic to eastern Australia. It is a terrestrial herb with a single, heart-shaped leaf and up to 18 small, translucent green or pinkish flowers with reddish marking and a green to reddish-purple labellum. It is widely distributed, growing in moist places from central-eastern Queensland, south through New South Wales and Victoria to South Australia and Tasmania.

<i>Caladenia clarkiae</i> Species of orchid

Caladenia clarkiae, commonly known as pink caps, is a plant in the orchid family Orchidaceae and is endemic to south-eastern Australia. It is a ground orchid which grows singly or in small groups in Victoria and New South Wales. It has a single leaf and usually one or two white to pale pink flowers with darker pink tips.

<i>Prasophyllum petilum</i> Species of orchid

Prasophyllum petilum, commonly known as the Tarengo leek orchid, is a species of orchid endemic to eastern Australia. It has a single tubular, green leaf and up to eighteen pinkish mauve to greenish flowers, well-spaced along a slender flowering stem. It is a small orchid, difficult to locate, generally growing in taller grasses.

<i>Prasophyllum montanum</i> Species of orchid

Prasophyllum montanum, commonly known as the mountain leek orchid, is a species of orchid endemic to eastern Australia. It has a single tubular, green leaf and up to fifty scented, greenish to pinkish flowers. It grows in montane ecosystems at altitudes above 1,500 m (5,000 ft).

<i>Prasophyllum dossenum</i> Species of orchid

Prasophyllum dossenum is a species of orchid endemic to a small area of northern New South Wales. It has a single tubular, dark green leaf and up to thirty scented pinkish-white and greenish-brown flowers crowded along an erect flowering stem. It is a rare orchid which grows in grassy places on the Northern Tablelands of New South Wales.

Prasophyllum erythrocommum is a species of orchid endemic to Victoria. It has a single tubular green leaf and up to thirty small, greenish brown to dark brown flowers. It is a very rare orchid, only known from a small area north of Melbourne.

Prasophyllum readii, commonly known as the Streathem leek orchid, is a species of orchid endemic to Victoria. It has a single, tubular leaf and up to twenty five scented, greenish-brown to reddish-brown flowers with a white or pinkish labellum and is only known from a swamp in the south-west of the state.

Prasophyllum crassum is a species of orchid endemic to South Australia. It has a single tube-shaped leaf and up to fifteen greenish and pinkish-brown flowers with a whitish labellum. It is a recently described plant, previously included with P. fitzgeraldii, but distinguished from that species by its smaller number of smaller, less colourful flowers and different labellum shape. It grows in the south-east of the state and usually only appears after fire.

Cyrtostylis tenuissima, commonly known as dwarf gnat orchid or dwarf mosquito orchid, is a species of orchid endemic to Western Australia. It usually has a single more or less round leaf and a flowering spike with up to fourteen small, green flowers with a greenish brown to pinkish, wedge-shaped labellum.

<i>Corybas acuminatus</i> Species of orchid

Corybas acuminatus, commonly known as the dancing spider orchid or helmet flower, is a species of terrestrial orchid endemic to New Zealand. It has a triangular, sharply pointed leaf and a small translucent, greenish-white flower with purple markings and with very long sepals. It is found on both the main islands of New Zealand and also some of the off-shore islands.

Corybas limpidus, commonly known as the crystal helmet orchid, is a species of terrestrial orchid endemic to Western Australia. It has round or heart-shaped leaf and a translucent greenish flower with dark red or burgundy-coloured spots and blotches. The edges of the labellum have a few short, blunt teeth.

<i>Acianthus cuneatus</i> Species of flowering plant

Acianthus cuneatus, commonly known as New England mosquito orchid, is a species of flowering plant in the orchid family Orchidaceae and is endemic to the Northern Tablelands of New South Wales. It is a terrestrial herb with a single, heart-shaped leaf and up to seven translucent greenish flowers with purplish stripes and is found growing in sheltered slopes in open forest.

Acianthus ledwardii was a species of flowering plant in the orchid family Orchidaceae and was endemic to Queensland in Australia but is now presumed extinct. It was a terrestrial herb with a single, heart-shaped leaf and between 2 and 6 transparent, reddish brown flowers.

<i>Acianthus saxatilis</i> Species of flowering plant

Acianthus saxatilis is a species of flowering plant in the orchid family Orchidaceae and is endemic to Queensland. It is a terrestrial herb with a single, relatively large, heart-shaped leaf and usually up to 5 translucent greenish-brown to greenish-yellow flowers.

References

  1. "Acianthus exiguus". Australian Plant Census. Retrieved 2 March 2023.
  2. 1 2 3 4 Copeland, Lachlan M.; Backhouse, Gary N. (2022). Guide to Native Orchids of NSW and ACT. Collingwood: CSIRO Publishing. pp. 6–7. ISBN   9781486313686.
  3. 1 2 3 4 5 6 7 Jones, David L. (1991). "New taxa of Australian Orchidaceae". Australian Orchid Research. 2: 7.
  4. 1 2 3 4 Jones, David L. (2006). A complete guide to native orchids of Australia including the island territories. Frenchs Forest, N.S.W.: New Holland. p. 162. ISBN   1-877069-12-4.
  5. 1 2 3 4 Jones, David L. "Acianthus exiguus". Royal Botanic Gardens Sydney:plantnet. Retrieved 17 June 2016.
  6. "Acianthus exiguus". APNI. Retrieved 16 September 2019.
  7. Lewis, Charlton T.; Short, Charles. "exiguus". A Latin Dictionary. Retrieved 17 June 2016.
  8. Kores, Paul J. (1995). "A systematic study of the genus "Acianthus" (Orchidaceae: Diuridae)". Allertonia. 7 (3): 202.
  9. "Acianthus fornicatus". Plants of the World Online. Retrieved 2 March 2023.
  10. "Acianthus". Australian National Botanic Garden. Retrieved 17 June 2016.