Family

Fabaceae

Distribution

Known only from the Douglas-Daly R. areas, N.T., where it occurs on cracking-clay soils.

Description

Trees to 5 m tall. Bark corky. Branchlets with scattered straight hairs 0.3 mm long. Stipules on flowering stems, sparse, straight, 0.7–1.5 mm long, to 5 mm on young plants, often wanting on mature plants. Leaves: axis 40–75 mm long (including petiole 5–8 mm), with scattered to moderately dense hairs on the broadly sulcate surface; gland disc-like, situated between the lowest pair of pinnae; pinnae 11–22 pairs, 15–30 mm long; pinnules 20–35 pairs, oblong, 1.6–2.2 mm long, 0.5–0.7 mm wide, thick, veins obscure, glabrous or with a few marginal hairs. Heads globular, 15–30-flowered; peduncles 25–40 mm long, with scattered long hairs, involucel in upper half. Flowers 5-merous; calyx gamosepalous; corolla 3–3.2 mm long. Pods c. 65 mm long, 10–15 mm wide, described as ‘creamy-coloured’, somewhat pubescent but becoming black and glabrous with age. Seeds longitudinal, oblong, c. 10 mm long, c. 9 mm wide; pleurogram prominent, open; areole large, depressed.

Specimens

N.T.: 2 km E of Douglas R. on Ooloo rd, 13°46’S 131°22’E, M.O.Rankin 1232 (BRI, CANB, DNA, K, MEL, NSW, NT, PERTH).

Notes

Its closest relative is V. bidwillii with V. clarksoniana more distant. It has more pinnules per pinna and the pinnules are smaller than those of V. bidwillii. It lacks the rather dense indumentum of V. clarksoniana and has smaller flowers. L.Pedley, Austrobaileya 6: 181 (2002), erroneously suggested that M.D.Tindale & P.G.Kodela, Austral. Syst. Bot. 9: 307–317 (1996), included elements of Acacia douglasica within their circumscription of A. ditricha, fide P.G.Kodela & P.G.Wilson, Telopea 11: 236 (2006) for discussion.

Based on molecular and other data Acacia sens. lat. is now considered as comprising a number of segregate genera, see J.T.Miller & D.S.Seigler, Austral. Syst. Bot. 25: 217-224 (2012) for overview. Many taxa in the former Acacia subg. Acacia are now referable to the genus Vachellia, including the one presented here. Vachellia douglasica was referred to by P.G.Kodela, Fl. Australia 11A: 202 (2001) as an undescribed species under Acacia bidwillii.

FOA Reference

Data derived from Flora of Australia Volumes 11A (2001), 11B (2001) and 12 (1998), products of ABRS, ©Commonwealth of Australia

Author

B.R. Maslin & P.G. Kodela