''Acianthus exsertus'', commonly known as gnat orchid or large mosquito orchid, is a species of flowering plant in the

orchid Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Orchids are cosmopolitan plants that are found in almost every habitat on Eart ...

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Orchidaceae and is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to eastern Australia. It is a

terrestrial Terrestrial refers to things related to land or the planet Earth, as opposed to extraterrestrial. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on o ...

herb Herbs are a widely distributed and widespread group of plants, excluding vegetables, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal purposes, or for fragrances. Culinary use typically distingu ...

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 Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...

the ACT and Victoria.

Description

''Acianthus exsertus'' is a terrestrial,

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

deciduous In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...

sympodial In botany, sympodial growth is a bifurcating branching pattern where one branch develops more strongly than the other, resulting in the stronger branches forming the primary shoot and the weaker branches appearing laterally. A sympodium, als ...

herb with a single heart-shaped,

glabrous Glabrousness () is the technical term for a lack of hair, down, setae, trichomes, or other such covering. A glabrous surface may be a natural characteristic of all or part of a plant or animal, or be due to loss because of a physical condition, ...

, dark green leaf that is reddish-purple on its lower surface. The leaf is long, wide. There are from 3 to 25 flowers, well-spaced on a thin

raceme A raceme () or racemoid is an unbranched, indeterminate growth, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are ...

, tall, each flower long. The

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 Etymology The term ''sepalum'' ...

is linear to egg-shaped, long, wide with a point long with a red central stripe and forms a hood only partly covering the

column A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member ...

. The

lateral Lateral is a geometric term of location which may also refer to: Biology and healthcare * Lateral (anatomy), a term of location meaning "towards the side" * Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx * Lateral release ( ...

sepals are long, wide, linear to narrow lance-shaped, with a tip long and project forwards parallel to each other or diverging. The petals are a similar colour and are long, about wide, linear to narrow egg-shaped and turn towards the ovary. The labellum is wide, wide, heart-shaped to elliptic, dished near the base with the edges rolled under but lacking teeth. The thick, fleshy

callus A callus (: calluses) is an area of thickened and sometimes hardened skin that forms as a response to repeated friction, pressure, or other irritation. Since repeated contact is required, calluses are most often found on the feet and hands, b ...

has many small pimple-like papillae on the outer half. Flowering occurs from March to August. This species is distinguished from other mosquito orchids by its relatively large, well-spaced, dark coloured flowers and by the dorsal sepal which does not cover the column.

Taxonomy and naming

''Acianthus exsertus'' was first formally described by

Robert Brown Robert Brown may refer to: Robert Brown (born 1965), British Director, Animator and author Entertainers and artists * Washboard Sam or Robert Brown (1910–1966), American musician and singer * Robert W. Brown (1917–2009), American printmaker ...

in 1810 and the description was published in ''

Prodromus Florae Novae Hollandiae ''Prodromus Florae Novae Hollandiae et Insulae Van Diemen'' (Prodromus of the Flora of New Holland and Van Diemen's Land) is a book by the botanist Robert Brown Robert Brown may refer to: Robert Brown (born 1965), British Director, Animator and ...

''. The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

(''exsertus'') is a

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word meaning to "stretch out" or "thrust out".

Distribution and habitat

This orchid is widespread and locally common, sometimes in coastal areas but more usually on the ranges and tablelands in sheltered forest and woodland, growing in well-drained soil. In Queensland, it occurs as far north as

Rockhampton Rockhampton is a city in the Rockhampton Region of Central Queensland, Australia. In the , the population of Rockhampton was 79,293. A common nickname for Rockhampton is "Rocky", and the demonym of Rockhampton is Rockhamptonite. The Scottish- ...

, in New South Wales in most regions of the coast and tablelands and in eastern Victoria, from sea level to an altitude of .

Conservation

''Acianthus exsertus'' is not threatened in New South Wales.

References

External links

* {{Taxonbar, from=Q8187423 exsertus Orchids of New South Wales Orchids of Queensland Orchids of Victoria (state) Endemic orchids of Australia Plants described in 1810 Taxa named by Robert Brown (botanist, born 1773)