Western underground orchid

Description

Rhizanthella gardneri, commonly known as western underground orchid, is a species of flowering plant in the orchid family and is endemic to the southwest of Western Australia. It is a herb that spends its entire life cycle, including flowering, at or below the soil surface. A head of up to 100 small reddish to cream-coloured, inward facing flowers surrounded by large, cream-coloured bracts with a horizontal rhizome is produced between May and July. Rhizanthella gardneri is a leafless, sympodial herb with a horizontal rhizome 60–120 mm (2.4–4.7 in) below the soil surface. Beginning in late May to early June, the plant produces up to 100 small, inward-facing pinkish to deep red and cream coloured flowers 4–5 mm (0.16–0.20 in) wide, surrounded by six to twelve pinkish-cream bracts. The bracts curve over the flowers, forming a tulip-like head and leaving a small opening at, or a few millimetres above the soil surface. After pollination, each flower produces a fleshy, berry-like fruit containing up to 150 seeds. Unlike the capsules of other orchids that produce minute, dust-like seeds dispersed by the wind, this species produces indehiscent fruit. Rhizanthella gardneri is only known from the Avon Wheatbelt biogeographic region of Western Australia, where it grows in association with broom honeymyrtle (Melaleuca uncinata), between Corrigin and Babakin. John Trott discovered the first specimen of R. gardneri during ploughing operations in May 1928 on his farm near Corrigin. The discovery generated such excitement that a wax model was toured around the British Isles. Specimens were found a further six times in similar circumstances between the Corrigin and Dowerin areas, until 1959. The next confirmed sighting was by John McGuiness near Munglinup in 1979, of plants in their natural habitat. In 1981 and 1982, surveys in the Munglinup area located more than one hundred flowering specimens. The Munglinup population is now regarded as the separate species, Rhizanthella johnstonii. Rhizanthella gardneri was first formally described in 1928 by Richard Sanders Rogers in the Journal of the Royal Society of Western Australia from specimens collected near Corrigin in May of the same year. The specific epithet (gardneri) honours Charles Gardner, assistant botanist to the Western Australian Government at that time.