Acianthus apprimusAcianthus apprimus, commonly known as early 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 between two and nine translucent pinkish flowers with reddish markings and is found in disjunct populations around the state.
DescriptionAcianthus apprimus 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 18-40 mm long, 14-35 mm wide on a stalk 4-9 cm high.
There are between two and nine flowers, well-spaced on a raceme 5-20 cm tall, each flower 9-12 mm long and about 7 mm across. The dorsal sepal is egg-shaped, 9-14 mm long, 4-6 mm wide, forms a hood over the column and is translucent pink with reddish veins and markings. The lateral sepals are 9-12 mm long, pinkish with a red stripe down the centre and cross each other below the labellum. The petals are a similar colour, about 4 mm long and project forward. The labellum is dark purplish-red to almost black, egg-shaped to lance-shaped, has a thick, fleshy callus covering most of the central area and many small pimple-like papillae on the outer half. It is 5.5-7 mm long, 2.5-4 mm wide with its edges turned under. This is one of the earliest-flowering Acianthus species and although it resembles Acianthus fornicatus, usually flowers between February and April, before the leaves of that species have emerged above ground. The capsule that develops is 6-8 mm long and 2-2.5 mm wide.
This species is distinguished from the similar Acianthus fornicatus by its folded labellum which leaves only the callus in view and by its very early flowering period - A. fornicatus flowers from May to August.