Arthrochilus byrnesii

Phoringopsis byrnesii is a terrestrial, perennial, deciduous, sympodial herb with an underground tuber which produces daughter tubers on the end of root-like stolons. It usually has three dark green leaves, one large and one or two smaller, each leaf 150–300 mm (6–10 in) long and 15–20 mm (0.6–0.8 in) wide. Between five and fifteen greenish, insect-like flowers 12–14 mm (0.5–0.6 in) long are well spaced along a flowering stem 150–300 mm (6–10 in) tall. The dorsal sepal is 8–10 mm (0.3–0.4 in) long, about 3 mm (0.1 in) wide and the lateral sepals are 6.5–7.5 mm (0.26–0.30 in) long and about 2.5 mm (0.1 in) wide. The petals are 6–7 mm (0.24–0.28 in) long and about 1.5 mm (0.06 in) wide and curved. The petals and lateral sepals turn backwards against the ovary and are inconspicuous. The labellum is about 5.5 mm (0.2 in) long and 2.5 mm (0.1 in) and held above the flower. The callus is about 5.5 mm (0.2 in) long, about 2.5 mm (0.1 in) wide, covered with many spiky, bristly hair-like glands with a glandular tip is about 2.5 mm (0.1 in) wide. Flowering occurs in March and April.

Sandstone truffle orchid is a rarely seen species which grows around sandstone boulders and in tussocks of spinifex in the north of the Northern Territory and the Kimberley region of Western Australia.

As with other Phoringopsis orchids, P. byrnesii is pollinated by male thynnid wasps of the genus Arthrothynnus although the species involved is not known. It also reproduces asexually by producing new tubers.

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