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Nuylsia Vol. 7, No. 2 (1990) 
(1978) included A. pravifolia F. Muell. and A. amblygona Cunn. ex Benth. with the A. deltoidea 
group as "the Triangulares group of Acacia section Plurinerves" and there is more than a passing 
resemblance between these species and the A. deltoidea group. Both species, however, have 
separate, lateral stipules, a bract subtending the base of the peduncles which are otherwise 
ebracteate, the heads are few-flowered and the bracteoles are of very different structure and texture 
than those of the present group. 
The A. deltoidea group is characterized by (1) small, inequilateral, pungent, sessile or 
sub-sessile phyllodes; (2) upwardly curving pairs of often partly connate (except A. sublanata and 
A. froggattii), persistent, subulate or acicular stipules located on the abaxial side of the phyllode 
base (except A. sublanata and A. froggattii), rather than laterally as in most species of Acacia; (3) 
all but A. sublanata have at least some of the hairs gland-tipped; (4) the peduncles are solitary, 
lacking a bract at their base but occasionally bearing one above their middle; (5) sepals and/or 
petals are partly united among themselves; and (6), most strikingly, some of the species have the 
staminal filaments united, up to one-fifth their length in A. stipulosa and basally in irregular 
fascicles in .4. adengonia. Such union of filaments is known in the 4. lycopodifolia group of 
species, which Pedley (1987) suggested as possible relatives, e.g., A. lycopodifolia Cunn. ex Hook, 
and A. hippuroides Howard ex Benth., as well as in other unrelated tropical species 
All measurements are from herbarium specimens unless otherwise indicated. The un-numbered 
taxa in the following key are not treated herein and are included only to indicate relationships. 
Key to taxa of A. deltoidea group 
1. Most phyllodes broadest below the middle, ovate to ovate-elliptic 
2. Phyllodes mostly 5-10 mm long, inequilaterally ovate, acuminate, pungent, 
gland often extending beyond phyllode margin in tooth-like projection; seeds 
longitudinal in pods 1-4. adenogonia 
2. Phyllodes 15-16 mm long, inequilaterally elliptic to elliptic-ovate, 
acute, not pungent, gland not extending beyond phyllode margin; 
seeds transverse 2b. 4. deltoidea subsp. ampla 
1 . Most phyllodes broadest at or above the middle 
3. Branchlets villose, hairs crisped, none gland-tipped; 
phyllodes broadly obdeltale 4. sublanata 
3. Branchlets other than villose, gland-tipped hairs always present; phyllodes of 
other shapes 
4. Calyx and corolla regularly 5-merous 
5. Branchlets with long, gland-tipped hairs and shorter, anLrorsely curved 
hairs A. froggattii 
5. Branchlets glandular-puberulous, hairs very short and patent sometimes 
with longer hairs intermixed 
6. Phyllodes 4-6 mm wide, inequilaterally elliptic or 
obdeltatc 2a. 4. deltoidea subsp. deltoidea 
6. Phyllodes 1.5-2 mm wide, inequilaterally oblong-oblanceolate, 
the margin between gland and apex strongly rounded 3.4. vincentii 
4. Calyx with up to 1 1 acuminate lobes, corolla 7- or 8-lobed 4. stipulosa 
