Acacia 
spaced, not anastomosing or only sparsely so in 
broader phyllodes, apex acute, mucro straight, oblique 
or slightly hooked. Glands inconspicuous, 1, at 
pulvinus. Inflorescences on simple axillary peduncles, 
mostly 2 per axil. Spikes pale yellow to white, 
15-40 mm long, 2-4 mm wide, flowers interrupted; 
peduncle 0.5-3 mm long, resinous, glabrous, rachis 
resinous, glabrous. Pods stipitate, brown, broadest 
towards apex and tapered to base, straight to curved, 
flat, opening elastically from apex, 50-90 mm long, 
5-6(10) mm wide, woody, glabrous, obliquely 
reticulately nerved although sometimes obscure, 
margin with (0.6)2-5 mm broad wing, acute and 
narrowing abruptly. Seeds oblique in pod, brown, 
narrowly oblong to ellipsoid, 5 mm long, 2.2-2.5 mm 
wide. Flowering and fruiting throughout the year 
but typically during the hottest months. Fig. 4 
In the Kimberley and Top End of the NT; rare in 
the DR where found associated with sandstone or 
sandy soils in Litchfield NP and Darwin R. area. 
A. helicophylla Pedley 
Erect spindly shrub, 2-4 m high, viscid. Bark 
reddish to brown to black, minni ritchi. Branchlets 
angular, viscid, sparsely hairy, hairs closely appressed, 
hyaline. Stipules persistent, reddish, triangular, 3 mm 
long, glabrous and resinous. Pulvinus 2-4 mm long, 
hairy. Phyllodes twisted, narrowly elliptic to elliptic, 
45-110 mm long, 5-28 mm wide, L/W 2.7-13, viscid, 
sparsely hairy, hairs closely appressed, hyaline but 
sometimes appearing yellow due to resin, 
primary veins 1, secondary veins parallel and widely 
spaced, sparsely or loosely anastomosing, base 
attenuate, apex obtuse, mucro straight, oblique or 
slightly curved to 3 mm long. Glands prominent, 
1, near base. Inflorescences on simple axillary 
peduncles. Spikes yellow, 20-35 mm long, 5-7 mm 
wide, densely flowered; peduncle 9-22 mm long, 
viscid, sparsely hairy, rachis glabrous. Pods shortly 
stipitate, brown, linear to oblong, slightly curved, 
raised over seeds, 30-60 mm long, 5-8 mm wide, 
coriaceous, sparsely to densely hairy, transversely 
reticulately nerved, acute. Seeds + longitudinal to 
oblique in pod, brown, flattened ellipsoid or 
rhomboid, 5-5.5 mm long, 4 mm wide. Flowering: 
Mar - Aug; fruiting: Apr - Dec. Fig. 5 
An NT endemic found scattered on sandstone 
from Katherine Gorge to Kakadu. In the DR sonly. 
known from Mt. Douglas. 
A. hemignosta F.Muell. 
Erect shrub or small tree, 2-5(7) m high, glaucous 
or pruinose. Bark grey, fissured. Branchlets slightly 
MIMOSACEAE ~ alt 
ribbed, pruinose, glabrous. Stipules caducous. 
Pulvinus 1.5-3 mm long, glabrous. Phyllodes straight 
or slightly curved, dimidiate or oblanceolate, narrowly 
to rarely broadly spathulate, 40-135 mm long, 5.5-35 
mm wide, L/W 2.8-20, pruinose, glabrous, primary 
veins 3, secondary veins obscure, reticulate, base 
attenuate, apex obtuse. Glands 1, near base. Inflores- 
cences extended axillary racemes or panicles or 
rarely on simple axillary peduncles, 8-27 heads per 
raceme, axis length 38-130 mm long. Heads globular, 
yellow, 4-6 mm wide; peduncle 3-10(14) mm long, 
often pruinose, glabrous. Pods stipitate, brown, 
linear to oblong, straight, raised over seeds with 
domed projections, 30-120 mm long, 9-15 mm wide, 
coriaceous, smooth, glabrous, faintly transversely 
reticulately nerved or nerves obscure, margin 
thickened, acute. Seeds brown, discoid, 5.5-6.5 mm 
long, 5.5-6.5 mm wide. Flowering: May - Oct but 
mostly June - July; fruiting: June - Nov. Fig. 5 
Widely distributed across northern Australia 
extending to the southern limits of the monsoon 
area (22° S). In the DR found in woodland on 
gravelly soils in the southern part of the region. 
A. holosericea Cunn. ex G.Don 
Erect ‘shrub, 2-5 m high. Branchlets flattened, 
densely sericeous or rarely glabrous, hairs hyaline. 
Stipules persistent, white, triangular, 1.5-2 mm long, 
pubescent. Pulvinus 7-9 mm long, hairy. Phyllodes 
straight, elliptic or dimidiate, broadest about 
middle, 100-225 mm long, 20-50(60) mm wide, 
L/W 3.5-6, usually densely sericeous or rarely 
glabrous, hairs hyaline, primary veins 3(4), concurrent 
with lower margin near base, secondary veins oblique 
or penniveined, reticulate, base attenuate, apex acute 
to obtuse, mucro straight. Glands prominent, 2, near 
mucro and near base. Inflorescences on simple 
axillary peduncles, 2 per axil. Spikes yellow, 42-55 
mm long, 3-6 mm _ wide, with flowers 
interrupted; peduncle 3-7 mm long, hairy, rachis 
glabrous. Pods shortly stipitate, reddish brown, 
linear to oblong, coiled and intertwined, persisting on 
rachis, raised over seeds, 4-5 mm wide, coriaceous, 
glabrous or with minute scattered hairs, nerves 
obscure, acute. Seeds longitudinal in pod, dark 
brown to black, oblong, 4-5 mm long, 2-3 mm wide. 
Flowering: June - Sept; fruiting: pods persisting 
throughout the year. Fig. 5 
Across northern Australia; common in the DR, 
especially on disturbed sites. Recent work (Maslin & 
Thomson, 1992) has segregated 2 further species 
(A. colei Maslin & L.Thomson and A. neurocarpa 
Cunn. ex Hook.) from the A. holosericea complex. 
Neither of these two taxa has been recorded in the DR. 
