Acacia macradenia

zig-zag branches


Acacia macradenia

Benth. 1848

pronounced: uh-KAY-shuh mak-ruh-DEEN-yuh

(Mimosaceae — the wattle family)

common name: zig-zag wattle

native 4Acacia is from the Greek ακις (akis), a thorn or spike; macradenia is from μακρος (makros), large and αδην (adén), a gland, referring to the large elongated gland on the phyllode margin.

In its natural habitat, Zig-zag wattle grows on stony or sandy soils on the understorey of open woodlands, often near creeks or on hillsides. In parts of eastern Queensland it has become naturalized along roadsides, in suburban parks and bushland, and in open eucalypt woodlands. Its native distribution is in central Queensland, from around Chinchilla to the Blackdown Tableland and at White Mountains near Pentland. There is another population near Tennant Creek.

Acacia macradenia is an attractive spreading shrub or small tree 3 – 5 m high with a spread of 3 – 4 m, with pendant to sub-pendant branches that noticeably zig-zag from node to node. The hairless dark green phyllodes (8 – 25 cm long and 8 – 25 mm wide) are tapered at both ends and vary from relatively straight to noticeably curved. They have a single prominent central vein running lengthwise, with persistent stipules at the base, and the phyllode margins are also raised and prominent. There is a large, elongated gland near the base, and often one or two smaller glands near the top margin. Young phyllodes and stems are often reddish in colour.

The large bright yellow ball flowers occur in winter and spring, and are followed by clusters of dark brown, smooth pods, raised over the seeds alternately and narrowed between the seeds. This is a very showy species that flowers in profusion if conditions are right. In coastal regions it seems to require a cold period, or even an extended cold period, to encourage flowering. The inflorescences are 8 – 15-headed racemes, prolific in the upper axils; the raceme axes are 2 – 5 cm long, glabrous; the peduncles 3 – 6 mm long, glabrous; the heads globular, densely 35 – 50-flowered, golden in colour. The flowers are pentamerous, the sepals about ¾ united.

The pods are up to 12 cm long and about 5 mm wide, thinly leathery, glabrous. The seeds are longitudinal, oblong, about 4 mm long, with a funicle-aril about the same length as the seed.

Because of its spectacular floral display in winter, this species has been widely cultivated in other parts of Australia as a garden ornamental. It is also often planted in revegetation projects in south-eastern Queensland as a “native” species; this is a serious mistake, as it is not native to those parts; it is spreading from these plantings and becoming a weed of bushland in many places: in the Maryborough area, and in the greater Brisbane area since 2003. Since then it has been reported from other parts of south-eastern Queensland, including the Gold Coast, the Sunshine Coast, and the Ipswich area.

Photographs taken in Nelly Bay, 2011
Page last updated 12th July 2019