Acaena novae-zelandiae

Acaena novae-zelandiae is a small herbaceous perennial. It is stoloniferous with prostrate stems of 1.5 – 2 mm diameter.[5] Damage to stolons encourages new shoots to be produced.[6]

Acaena novae-zelandiae, Tasmania, Australia.

It has imparipinnate leaves, with 9–15 toothed, oblong leaflets, which are approximately 2 –11 cm long.[5] The adaxial surface of the leaves is dark green and shiny, and the abaxial surface is hairy and glaucous green in colouration.[2][5][7] The rachis of the leaves is often red.[5]

The scape is 10 – 15 cm long[5] and bears a globular, terminal inflorescence, of 20 – 25 mm diameter,[2] with 70 – 100 flowers.[5][7] The flowers lack petals and can range in colour from green to white or purple.[8] The flowers are wind pollinated.[6]

Acaena novae-zelandiae seeds on a glove, demonstrating their ability to attach easily to articles of clothing.

Each flower produces one achene, bearing four approximately 10 mm long spines,[2] tipped with barbs,[2][5][7] which aid dispersal by attaching to wool, feathers and various clothing materials.[9] When the fruit are ripe, these spines are red in colouration, later becoming brown.

Acaena novae-zelandiae was first formally described in 1871 by Thomas Kirk who published the description in Transactions and Proceedings of the New Zealand Institute.[10][11] The genus name (Acaena) is derived from the Ancient Greek word akaina meaning "thorn" or "spine",[12] referring to the spiny calyx of many species of Acaena. The specific epithet (novae-zelandiae) refers to New Zealand.[1]

Red bidibid is native to New Zealand, Australia and New Guinea. It has also become naturalised in California, Great Britain and Ireland.[5] It is regarded as invasive in Great Britain where it has established itself in places such as dune habitats on Lindisfarne.[13][14]

It occurs within a wide range of habitats, including woodlands, shrublands and grasslands, from coastal areas to alpine areas.[2][7] It grows in freely draining soils such as silty and sandy loams, typically on sites which receive a high amount of sunlight.[7]

It also establishes readily on disturbed sites such as roadsides.[9]

Acaena novae-zelandiae may be used for ground cover in gardens or as a lawn substitute. This plant can be prevented from spreading by limiting disturbance to stolons, thus reducing vegetative propagation,[6] and by mowing flowers before the burrs form.[15]

It has also been suggested that dried "tiny tips"[16] of young succulent leaves may be brewed as tea.[15][16][17][18]