Muehlenbeckia axillaris
This is one of several plants called pōhuehue. Male and female flowers are on separate plants. It is a perennial with branches that spread sideways through the soil and/or root at the nodes[1]. Spread is fairly rapid - our 2 plants easily filled an 3.2 m space in about 12 months.
Muehlenbeckia axillaris is the dark green groundcover in this photo. It is surrounding a Muehlenbeckia astonii shrub, with several other native shrubs behind them.
Staminate (male) flowers.
Muehlenbeckia axillaris leaves and flowers.
Side view of a Muehlenbeckia axillaris plant - our plants have reached more than 30 cm height.
Arrangement of leaves and flowers on Muehlenbeckia axillaris.
Root system of Muehlenbeckia axillaris, from a planter bag.
Somewhat leathery leaves, that are darker on top than below.
Muehlenbeckia axillaris is frost hardy.
A study on how resistant some ground covers are to preventing weeds from establishing beneath them found that Muehlenbeckia axillaris was quite effective - mainly by changing the amount of red light to far-red light that reaches the ground beneath[2].
References
1. Allan HH et al. (1961) Flora of New Zealand. Volume I. Government Printer.
2. Foo C, Harrington K, MacKay M (2011) Weed suppression by twelve ornamental ground cover species. New Zealand Plant Protection Society 64:149–154.