Upper and lower (purplish) leaf surfaces of A. fornicatus
Acianthus fornicatus, commonly known as bristly mosquito orchid[2] or pixie caps,[3] is a species of flowering plant in the orchidfamily Orchidaceae and is endemic to eastern Australia. It is a terrestrialherb 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.
Description
Acianthus fornicatus is a terrestrial, perennial, deciduous, sympodial herb with a single heart-shaped, glabrous, dark green leaf which is reddish-purple on its lower surface. The leaf is 10–40 mm (0.4–2 in) long, 10–20 mm (0.4–0.8 in) wide on a stalk 4–9 cm (2–4 in) high.[3][4]
There are up to ten flowers, well-spaced on a raceme 100–300 mm (4–10 in) tall, each flower 10–40 mm (0.4–2 in) long and translucent, pinkish-red with a green, sometimes blackish labellum. The dorsalsepal is broadly egg-shaped, 9–12 mm (0.4–0.5 in) long, 5–6 mm (0.20–0.24 in) wide and forms a hood over the column. The lateral sepals are 9–12 mm (0.4–0.5 in) long, 1.4 mm (0.06 in) long wide with tips 2–4 mm (0.08–0.2 in) long and may be crossed or parallel to each other. The petals are about 4 mm × 1 mm (0.2 in × 0.04 in) long and spread widely. The labellum is green, rarely blackish, egg-shaped to lance-shaped, with the outer edges turned under. When flattened, it is heart-shaped, 5–6 mm (0.20–0.24 in) long, 2.5–3 mm (0.098–0.12 in). There is a thick, fleshy callus covering most of the central area and many small pimple-like papillae on the outer half. Flowering occurs between May and August.[2][3][4]
This species is distinguished from others in the genus by its largish, projecting flowers, usually pinkish colouring, and broad dorsal sepal and labellum.[4]
This mosquito orchid is widespread and common in coastal and near-coastal areas in heathy forest and coastal scrub, growing in well-drained sandy loam. It occurs in Queensland and in New South Wales as far south as Eden.[4][3]
Conservation
Acianthus fornicatus is not threatened in New South Wales,[3] but is classified as threatened in Victoria, where it is found only on Gabo Island.[8]
^ abCopeland, Lachlan M.; Backhouse, Gary N. (2022). Guide to Native Orchids of NSW and ACT. Collingwood: CSIRO Publishing. pp. 10–11. ISBN9781486313686.
^ abcdeJones, David L. "Acianthus fornicatus". Royal Botanic Gardens Sydney:plantnet. Retrieved 18 June 2016.
^ abcdJones, David L. (2006). A complete guide to native orchids of Australia including the island territories. Frenchs Forest, N.S.W.: New Holland. p. 162. ISBN1-877069-12-4.
