Family

Fabaceae

Distribution

Of scattered occurrence in the Pilbara region of north-western W.A. where it is recorded from around Karratha, Millstream, Panawonica, Paraburdoo and on Hillside and De Grey stations.

Description

Bushy, spreading, glabrous shrub or tree 2–5 m high. Phyllodes spreading to erect, commonly linear, sometimes narrowly oblanceolate or narrowly oblong elliptic, straight to shallowly curved, (8–) 9–14 (–16) cm long, (2–) 3–10 (–15) mm wide, not rigid, green; midrib rather prominent; gland 0–6 (–15) mm above pulvinus, a smaller gland at or near base of mucro. Inflorescences racemose, the racemes 3–20 mm long often growing out (with the subsequent inflorescences simple); peduncles 8–20 mm long; heads lemon yellow, sub-densely 15–25-flowered. Flowers 5-merous; calyx ±truncate. Pods submoniliform, breaking readily at constrictions, 8–13 cm long, 8–12 mm wide, woody, yellowish brown. Seeds longitudinal, oblong to elliptic, 7–9 mm long, 4.5–7 mm wide, rather turgid, dark brown to blackish; aril rather small, orange to brown when dry (?red when fresh).

Phenology

Flowers July–Aug.

Habitat

Grows on floodplains, clay pans or along watercourses; around Karratha it occurs in the coastal dunes along seasonally dry creeks.

Specimens

W.A.: Back beach, Karratha, G.Craig 393 (PERTH); Bamboo Springs Stn, 35 km NW of Bonnie Downs HS on rd to Hillside Stn, B.R.Maslin 8506 (CANB, MEL, PERTH).

Notes

The hybrid status of this entity is based on field observations and morphology of specimens examined; it has been found in a number of populations (at a low frequency) with both presumed parents. The putative hybrids are recognized by their lemon yellow heads (white in A. ampliceps, golden in A. sclerosperma subsp. sclerosperma) and their phyllodes (and to some extent their pods) which are intermediate in width between the putative parents. In the Pilbara A. ampliceps also hybridizes with A. bivenosa (see A. ampliceps × bivenosa for discussion). Acacia ampliceps × sclerosperma subsp. sclerosperma is sometimes sympatric with A. bivenosa × sclerosperma subsp. sclerosperma (see the latter for discussion). For further information see B.R.Maslin et al., Wattles of the Pilbara CD-ROM (2010).

FOA Reference

Flora of Australia Project

Author

B.R.Maslin