Acaena anserinifolia

The bidibidi is a small plant with deeply divaricated opposite leaflets and long stems ending in a globular capitulum. The flowers are pink, red, or white.^[3]

It can be distinguished from Acaena novae-zelandiae by "the distinctive tuft of brush-like hairs surmounting the leaf teeth apices," and by silvery leaf undersides.^[3]

The species was first described as Ancistrum anserinifolium in 1775 by Johann Reinhold Forster and Georg Forster; father-and-son naturalists who came to New Zealand aboard the Second voyage of James Cook. Their work was published in the book Characteres generum plantarum.^[4] In 1880, Joseph Beattie Armstrong recombined the species, placing it in the genus Acaena,^[5] which remains the current accepted scientific name today.^[2]

The Māori language name piripiri is used for a variety of Acaena species found in New Zealand. Piri is a word used across various Polynesian languages for sticky plants.^[6] Other Māori language names for the plant include huruhuru o Hine-nui-te-pō ("feathers of Hine-nui-te-pō"), pirikahu, hutiwai; many other names include the elements kaiā (thief) and rure (scatter), including kaiā, kaikaiārure and kaikaiā.^[6] The English language name biddy-bid is based on a mishearing of the Māori word piripiri, and over time the word biddy developed as a verb in New Zealand English, meaning to remove seeds from clothing.^[6]

The species epithet, Anserinifolia, is a reference to the leaves, which are like Potentilla anserina.^[3]

The species' ability to attach seeds to clothing likely evolved as a way to disburse seeds by attaching to the feathers of flightless birds, including kiwi, weka and moa.^[6]

Acaena anserinifolia is native to the North Island, South Island, Stewart Island, and the Chatham Islands in New Zealand. It has been introduced to Antipodean Islands, Great Britain and Ireland.^[7] It is naturalised on the Auckland Islands and Campbell Island.^[3] The plant grows in lowland to subalpine areas, and on forest edges. They are sometimes hydrorphytic.^[3]

Boiled piripiri leaves are used in traditional rongoā medicinal practices, either as a healing tonic or a lotion applied to skin. Smoke from burning piripiri was a traditional remedy for people who had been poisoned by tutu.^[6][8]