Australian Tropical Rainforest Orchids

Trachyrhizum agrostophylla

Buttercup Orchid

Trachyrhizum agrostophylla (F.Muell.) Rauschert, Feddes Repert. 94(7-8): 469 (1983).

Dendrobium agrostophyllum F.Muell., Fragm. 8: 28-9 (1873); Callista agrostophylla (F.Muell.) Kuntze, Revis. gen. pl. 2: 654 (1891). Type: Ad sinum Rockingham’s Bay, J. Dallachy s.n. (holo MEL; iso K).

Dendrobium muellerianum Schltr., Repert. Spec. Nov. Regni Veg. Beih. 3: 316 (1907). Type: Queensland: Auf dem Mount Bartle Frere, 1892, S. Johnson s.n. (holo B).


Occurs in north-eastern Queensland from the Big Tableland to Mt Spec near Ingham.

Altitude: 650-1600 m.


Epiphytic or lithophytic herb with creeping habit forming slender clumps. Rhizome creeping, appressed to host, 5 mm wide, branching every 3-5 nodes. Pseudobulbs widely spaced, erect, very narrowly fusiform, 10-60 cm x 0.5-1 cm, yellowish, furrowed. Leaves 8-20, scattered along upper half of pseudobulb, widely spaced, erect to prostrate, distichous, alternate, sessile, bases sheathing stem; lamina narrowly ovate, 4-10 cm x 0.8-1.2 cm, dark green, thin-textured but tough, apex unequally emarginate. Inflorescence an axillary raceme, 20-50 mm long, emerging opposite a leaf; pedicels arching, 10-20 mm long. Flowers 2-10, resupinate, porrect to nodding, 10-15 mm x 15-20 mm, bright yellow, waxy, fragrant. Sepals and petals projecting forwards, flowers remaining cupped. Dorsal sepal ovate, 7-9 mm x 5-6 mm. Lateral sepals ovate to broadly triangular, 7-9 mm x 6-7 mm, bases fused to column foot. Petals incurved, spathulate, 6-8 mm x 5 mm. Labellum 9 mm x 6 mm, 3-lobed; lateral lobes incurved; midlobe with 2 flared lobes and 2 ridges. Column 3 mm long. Column foot 9 mm long, at right-angles to column. Capsules pendulous, dehiscent.


Occurs in rainforests and in gullies and humid areas of open forests, growing on trees. In open forest the plants can be stunted with small pseudobulbs and short leaves. Each pseudobulb takes more than a year to complete its growth, with new growths developing as previous ones are maturing. Plants growing in litter accumulation on boulders can form dense patches. The flowers are sweetly perfumed.

Widespread and common.

Flowering period: July-November.

Name Changes

Until recently known as Dendrobium agrostophyllum.

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