Pomatocalpa macphersonii

Pomatocalpa macphersonii is an epiphytic or lithophytic herb with a single main flattened stem, 50–100 millimetres (2.0–3.9 in) long and thick, cord-like roots. There are between two and eight dark green, thin, stiff oblong leaves 150–250 mm (5.9–9.8 in) long and 30–35 mm (1.2–1.4 in) wide.

Between three and thirty cup-shaped yellow flowers with red blotches, 7–10 mm (0.28–0.39 in) long and wide are borne on an stiff flowering stem 15–40 mm (0.59–1.6 in) long and hanging downwards. The sepals and petals are 3–5 mm (0.12–0.20 in) long, about 2.5 mm (0.098 in) wide. The labellum is white with a red blotches, 3–4 mm (0.12–0.16 in) long, 4–5 mm (0.16–0.20 in) wide with three lobes. The side lobes are erect and the middle lobe is fleshy and downturned with a spur about 2 mm (0.079 in) long. Flowering occurs from July to October.[2][3][4]

The blotched bladder orchid was first formally described in 1870 by Ferdinand von Mueller as Saccolabium macphersonii. He published the description in Fragmenta phytographiae Australiae from a specimen collected by John Dallachy near Rockingham Bay in Queensland.[5][6] In 1958 Trevor Hunt changed the name to Pomatocalpa macphersonii.[7] The specific epithet (macphersonii) honours John Alexander MacPherson.[6]

Plectorrhiza macphersonii usually grows on the trunks and large branches of trees in rainforest at altitudes up to 1,000 m (3,300 ft). It is found in New Guinea and in Queensland on the Cape York Peninsula and as far south as Rockhampton.[2][3][4]