Apostasia wallichii, commonly known as the yellow grass orchid,[1] is a species of orchid that is native to India, Japan, China, Southeast Asia, New Guinea and northern Australia. It has many arching, dark green, grass-like leaves and up to forty small, star-like yellow flowers arranged on a branched flowering stem. It mainly grows in wet forest and rainforest.
Apostasia wallichii is a terrestrial, tuberous, evergreen herb, scarcely recognisable as an orchid. It has wiry, branched roots with fleshy, warty projections and an erect, fibrous stem with many grass-like leaves arranged in whorls along it. The leaves are dark green, thin and leathery NaNsigfig=1NaNsigfig=1 long and up to 1sigfig=1NaNsigfig=1 wide. Between five and forty star-like, yellow flowers, NaNsigfig=1NaNsigfig=1 wide are arranged on branched flowering stems NaNsigfig=1NaNsigfig=1 long and arising from leaf axils. The three sepals and three petals are all similar in size (NaNsigfig=2NaNsigfig=2 long, NaNsigfig=1NaNsigfig=1 wide), shape (narrow triangular) and colour. Flowering occurs between December and March in Australia and in August in China.[2] [3] [4]
Apostasia wallichii was first formally described in 1830 by Robert Brown. Brown's manuscript was published in Nathaniel Wallich's book, Plantae Asiaticae Rariores.[5] [6] The specific epithet (wallichii) honours Nathaniel Wallich.
The yellow grass orchid grows in tropical forest and rainforest, sometimes near streams at altitudes of up to 1000sigfig=1NaNsigfig=1. It is found in Hainan, south-west Yunnan, Bangladesh, Cambodia, India, Indonesia, southern Japan, Nepal, Malaysia, Myanmar, Sri Lanka, Thailand, Vietnam, the Philippines, New Guinea and Queensland where if occurs between Bamaga and Ingham.