Acacia helicophylla Pedley, Contr. Queensland Herb . 15: 11; 20, fig. 2A & 25, fig. 7 (1974)
Viscid shrub to 4 m high. Bark ‘Minni Ritchi’, peeling in strips, grey, red-brown to blackish. Upper branchlets slightly angular, otherwise terete, densely appressed-puberulous and with broad, irregular bands of resinous tissue. Phyllodes narrowly oblong to elliptic or oblanceolate, undulate or spirally twisted, (3.5–) 5–12.5 cm long, (4–) 6–30 mm wide, narrowed towards base, obtuse to retuse with a dark fine mucro to 3 mm long at apex, minutely tuberculate, hairy mostly on 6–8 longitudinal nerves and margins, with prominent midnerve and 2–4 subprominent nerves, the minor nerves 2 per mm, coarsely reticulate; gland 1, basal, to 6 mm above pulvinus. Spikes 1 or 2 in axils, 1.5–3.5 cm long, yellow. Flowers 5-merous, longitudinally striate; calyx 0.6–1.2 mm long, dissected to 1/2, glabrous; corolla 1.4–2 mm long, dissected to 1/2–2/3, glabrous; ovary glabrous or slightly hairy. Pods narrowly oblong, sometimes slightly constricted between seeds, septate, curved apiculate, (1.8–) 2.5–7 cm long, 5–8 mm wide, thinly coriaceous, reticulately nerved, with fine hyaline hairs to 1.2 mm long or subglabrous. Seeds longitudinal, elliptic, turgid, 4.5–5.7 mm long, dark brown; areole orbicular, small, closed, often paler than rest of seed and surrounded by a pale halo.
Restricted to tropical N.T. in a small area between Katherine Gorge and Gunlom (UDP) Falls. Grows amongst rocks on sandstone cliffs and steep hillsides, in sandy, skeletal soils. Flowers Mar.–Aug.
The spirally twisted phyllodes with up to five or six turns in young plants are unique in Acacia . The curved, apiculate, septate pods are also unusual. The striate flowers are similar to some tropical species in sect. Lycopodiifoliae but the phyllodes are quite different.
Representative collections
N.T.: Edith Falls, L.G.Adams 1763 (BRI, CANB, K, L, MEL, NSW, NT, US); UDP Falls, N.Byrnes 1782 (DNA, NSW); Katherine Natl Park, cult., M.D.Tindale 6026 (NSW).
Type of accepted name
Katherine Gorge Natl Park, N.T, Apr. 1968, N.Byrnes 620 ; holo: BRI.
Illustrations
L.Pedley, op. cit. 25; J.Brock, Top End Native Pl. 53, 62 (1988); M.Simmons, Acacias Australia 2: 277 & pl. 15 (1988).
(NSW)
The information presented here originally appeared on the WATTLE CD-ROM which was jointly published by the Australian Biological Resources Study, Canberra, and the Department of Parks and Wildlife, Perth; it was produced by CSIRO Publishing from where it is available for purchase. The WATTLE custodians are thanked for allowing us to post this information here.
