Common Name

Ring-pod Minnie Ritchi

Family

Fabaceae

Distribution

Occurs in the NW Kimberley region of northern W.A. where it grows along the Prince Regent R. Populations are usually large but composed of plants scattered over broken sandstone over several kilometres.

Description

Sprawling, decumbent to semi-erect, viscid shrub to 0.6 (–1) m tall. Bark ‘Minni Ritchi’ at base of mature stems. Branchlets normally glabrous. Stipules persistent, triangular, c. 1 mm long. Phyllodes narrowly linear or sometimes linear-elliptic, narrowed at base, (4–) 5–8.5 cm long, (1–) 1.5–2.5 mm wide, acuminate by a fine, normally curved, innocuous point, often spreading at irregular angles, thin-textured and not rigid, flat, glabrous or sparsely, ±silky appressed-hairy; multinerved with central nerve the most pronounced, the upper margin broader than lower margin; gland basal. Inflorescences simple; peduncles 12–25 mm long, noticeably longer than spikes, glabrous or sparsely appressed, ±silky-hairy, a single brown bract near or above middle; spikes obloid to short-cylindrical, mostly 9–12 x 6–7 mm (when dry). Bracteoles c. 1.5 mm long, acuminate. Flowers 5-merous; sepals slightly exceeding ½ length of petals, free, linear, glabrous; petals glabrous, obscurely striate. Pods strongly curved into an open circle or coil, 5–7 mm wide, glabrous, very viscid (especially when young), marginal nerve thick. Seeds longitudinal, obloid, 4.5–5 mm long, 3–3.5 mm wide, dark brown to blackish except dull cream at centre; areole small (0.8–1 × 0.5–0.6 mm), not open at the hilar end.

Phenology

Flowers predominantly in the wet season from Jan.–Apr.; pods with mature seeds collected in Apr. and Aug.

Habitat

Grows in association with Acacia orthocarpa, A. prolata, Auranticarparesinosa, Borya subulata, Eucalyptus miniata, E. phoenicea, E. rupestris,Livistona lorophylla, Owenia vernicosa and Triodia claytonii.

Specimens

W.A.: [localities withheld for conservation reasons] R.L. & M.D.Barrett 1721 (MEL, PERTH); R.L. & M.D.Barrett 2632 (DNA, PERTH); K.F.Kenneally 2078 (NSW, PERTH); T.Willing s.n. (BRI, DNA, MEL, PERTH 07386567).

Notes

A variant of uncertain taxonomic status occurs in the SW Edkins Ra. (e.g. R.L.Barrett, M.D.Barrett & B.M.Anderson RLB 7984, PERTH). See B.R.Maslin, M.D.Barrett & R.L.Barrett, Nuytsia 23: 554–555 (2013) for discussion.

Most closely related to A. trachycarpa which is common in the Pilbara region, W.A., c. 1,000 km SW of where A. cyclocarpa occurs. Acacia trachycarpa is distinguished by its normally taller stature, longer and narrower spikes, united, golden-hairy sepals, 1-nerved petals, shorter bracteoles, broader pods that are hairy (at least when young) and oblique, larger seeds; it also has generally shorter peduncles. Also related to the Kimberley endemic, ‘Minni Ritchi’ species A. minniritchi which is most readily distinguished by its taller stature, longer spikes and pilose pods.

Conservation

Acacia cyclocarpa is listed as Priority Three under Department of Parks and Wildlife Conservation Codes for Western Australian Flora.

FOA Reference

Flora of Australia Project

Author

B.R.Maslin