Acianthus exiguus
Acianthus exiguus, commonly known as tiny mosquito orchid, 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. 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 long, wide on a stalk high . There are up to five flowers well-spaced on a thin raceme tall, each flower long. The dorsal sepal is oval to elliptic in shape, long, wide, translucent greenish-white with faint red markings and forms a hood over the column. The central vein extends about beyond the end of the labellum. The lateral sepals are long, about 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 long, narrow egg-shaped to lance-shaped and usually  spread widely. The labellum is pink to pinkish-mauve, wide, about 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. This species is distinguished from other mosquito orchids by its small, greenish, semi-erect flowers and narrow, purplish labellum. 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. The specific epithet ("exiguus ) is a Latin word meaning small", "little" or "petty". In a 1995 paper published in the journal "Allertonia", Paul Kores claimed that "A. exiguus" and four other species are not distinct from "A. fornicatus" and should be regarded as a synonyms. That position has been adopted by the Royal Botanic Gardens, Kew. Ecology. The flowers of this species, unlike those of other mosquito orchids, are self-pollinating. Distribution and habitat. This orchid grows in localised populations between Repton and Wardell in the North Coast region of New South Wales. It grows in sandy soil and clay loam in tall, moist  forest and rainforest. Conservation. "Acianthus exiguus" has a ROTAP rating of 3RC-, indicating that it is uncommon.