It is found in both, the North and the South Islands and has distinctive small heart-shaped deciduous leaves amidst a tangle of wiry interlocking branches.

The seed is a dark three-sided nut, about 2–2.5 millimetres (0.079–0.098 in) long, dull not glossy (which distinguishes it from the scrub pōhuehue or torararo, M.

[4]Muehlenbeckia astonii was first described by botanist Donald Petrie in 1911, and named Muehlenbecki Astoni after Bernard Aston, who collected the specimens in Palliser Bay at the mouth of the Wainuiomata River in 1908.

It sometimes goes by the names wiggy-wig bush,[note 1] zig zag plant,[8] wirebrush,[9] shrubby pōhuehue,[4] or mingimingi (a generic term for many small-leaved shrubs).

[1] Its former range is hard to determine, as the species was only recognised by botanists decades after most of New Zealand's dry scrublands had been cleared for agriculture.

[4] Its deep root system helps it survive in dry conditions, and can grow on open rocky hillsides and stony ground, up to 300 metres (980 ft) altitude.

[4] Originally M. astonii would have grown in the dry scrub habitat known as "grey scrub", in association with grasses or sedges and small-leaved shrubs such as Rubus squarrosus (leafless lawyer), Olearia solandri (coastal tree daisy), and Discaria toumatou (matagouri).

[1] These habitats were some of the first in New Zealand to be cleared for agriculture during colonisation, and so most individual M. astonii now are surviving in heavily modified open grassland.

[3] Plants suffer from trampling and browsing by livestock and other introduced mammals such as rabbits, hares, and possums, and seedlings are eaten by slugs and snails.

[8] Open agricultural land is a poor habitat for shrubby tororaro, but is suitable for the other scrambling and climbing members of the genus (M. complexa and M. australis) which both compete with and hybridise with M.

[4] Three wild populations (at Cape Campbell, Balmoral Conservation Area, and Kaitorete Scientific Reserve) have legal protection and are undergoing restoration.

[13] Once threats are removed, wild populations of M. astonii appear to respond rapidly, so there is an excellent chance that this endangered species will recover.