When I revised the Australian species of Aceratium (van Balgooy, 1963) no good flowering material was available of A. ferrugineum. By then the species had only been collected four times, all in rainforest on Mt. Spurgeon and Mt. Lewis in NE Queensland. Although more material of this apparently rare Australian endemic has been collected since, no flowering material became available until November 28, 1974, when Bernie Hyland found a tree of this species in flower. He kindly sent me flowers preserved in F.A.A. for study and completion of my earlier description. The notes that follow are based mainly on this collection, B. P. M. Hyland 7885, State Forest Reserve 143, North Mary Logging Area, 16°30' S, 145°15'E, in rainforest at 1200 m, and on van Balgooy 1621, collected on August 13, 1971 on Mt. Misery in rainforest at c. 1200 m. Inflorescence racemose, 15 mm long, with 8—10 flowers decussately arranged, on pedicels 8—10 mm long; peduncle and pedicels densely tomentellous. Flowers 5-merous. Sepals narrowly lanceolate, 14—16 mm long 3—4 mm broad, with raised midrib inside, densely tomentellous outside, very short velutinous inside. Petals pink-red (in vivo), narrowly spathulate, 18—20 mm long, 5—7 mm broad at top, apex either three-lobed, each lobe indented, or apex irregularly dentate, midrib raised inside in lower half of the petal, the lower two thirds of the margin, the midrib and the base of the petal inside covered with soft hairs generally pointing backwards. Disk c. 1 mm high, with weak episepalous lobes, strigose. Stamens 15, arranged in groups of three opposite the sepals inserted inside the disk, the middle stamen more central than the outer two. Filaments sigmoid or curved at the end, 5—7 mm long, tapering to the top, glabrous; anthers linear, 3.9—4.1 mm long, minutely puberulous, setiferous at the apex. Ovary ovoid, 4—5 mm long, densely strigose, three-locular, each cell containing four axillary, pendulous, anatropous ovules in two rows. — Fig. 1a—g.