Corunastylis

Corunastylis tepperi, commonly known as pygmy orchid, is the only species in the flowering plant genus Corunastylis in the orchid family, Orchidaceae and is native to Victoria, South Australia and Western Australia. It is a terrestrial herb with a single leaf mostly surrounding the stem and up to 50 flowers. The flowers are tiny with a deep maroon-coloured labellum and often have a fruity fragrance.

Description

Corunastylis tepperi is a terrestrial, perennial, deciduous, sympodial herb. A single long leaf surrounds the stem from the base of the plant to the lowest of the flowers. The leaf is 8–20 cm (3–8 in) long and 1–2 mm (0.04–0.08 in) wide.^[2][3]

The inflorescence is a spike with from 5 to 50 crowded, tiny, non-resupinate flowers which are bright green with a dark maroon-coloured to purplish-black labellum. Each flower is pendulous, about 3 mm (0.1 in) wide and long with petals and sepals that do not spread widely. The dorsal sepal is a broad egg-shape, about 2 mm (0.08 in) long and wide. The two lateral sepals are lance-shaped, 2.5–3.5 mm (0.098–0.14 in) long and about 1 mm (0.04 in) wide and dished near their base. The petals are egg-shaped, about 2 mm (0.08 in) long and less than 1 mm (0.04 in) wide. The dark-coloured labellum is egg-shaped, about the same size as the petals with a minutely wavy edge. The callus is narrow egg-shaped and extends almost to the tip of the labellum. The column, which is below the labellum has wings with a rough surface. Flowering occurs between February and May and the fruit that follows is a non-fleshy, dehiscent capsule containing hundreds of seeds.^[2][3]

Taxonomy and naming

In 1880, Otto Temper, a South Australian school teacher, reported to the Royal Society of South Australia, the discovery he had made of an orchid "in respect of which Baron F. v. Mueller, has done me the honour of naming it Prasophyllum Tepperi".^[4][5] Tepper's description was formalised by Ferdinand von Mueller in 1882 with the name published in Systematic Census of Australian Plants.^[6][7]

In 1888, Robert Fitzgerald first formally described Corunastylis apostasioides and published the decription in Australian Orchids, the first time the name Corunastylis was used.^[8] In 1889, Mueller changed the name to Prasophyllum apostasioides^[9] and in 1989, David Jones and Mark Clements placed it and most other species of Prasophyllum into Genoplesium^[10] leaving Corunastylis tepperi as the only remaining species in the genus. Subsequently, in 2002 Jones and Clements have proposed moving all but one of Genoplesium back to Corunastylis but the move has not been widely accepted.^[11][12]

The genus name Corunastylis is derived from the Ancient Greek words koryne meaning "club" or "mace"^[13]:213 and stylos meaning "column" or "pillar"^[13]:54 referring to the shape of the style.^[14] The specific epithet (tepperi) honours Otto Tepper.^[5]

Distribution and habitat

Pygmy orchid occurs in arid areas of north-western Victoria, mostly in mallee shrubland and Callitris woodland,^[3] and in the Avon Wheatbelt, Coolgardie, Esperance Plains, Hampton and Mallee biogeographic regions of southern Western Australia.^[15] There are also isolated populations in South Australia.^[16] It is a very drought and heat tolerant species which is dormant when the soil is hard-packed and dry, growing and flowering in the cooler, wetter autumn months.

Ecology

This species appears to be pollinated by tiny fuit flies which are attracted by the scent of the flower at the same time as other plants, such as Leucopogon are flowering.^[2][17][18]

References