Acaena microphylla, the bidibid or piripiri, and outside New Zealand, New Zealand-bur,[1] is a small herbaceous, prostrate perennial flowering plant in the rose family Rosaceae, native to both the North and South Islands of New Zealand.[2] There are two varieties:
There are no synonyms.[2]
Hooker describes it as "a very small and glabrous species; the leaflets not 1/4 in. long. Capitula very large for the size of the plant, upwards of an inch across, including the spines, which are not barbate, and distinguish it as a species."
Acaena microphylla was first formally described in 1852 by Joseph Dalton Hooker.[2] The genus name Acaena is derived from the ancient Greek word akaina, meaning "thorn" or "spine",[3] referring to the spiny calyx of many species of Acaena. The specific epithet microphylla derives from the Greek words, (small) and (leaf), to give an adjective meaning "small-leaved".[4]
It is found on both the North Island and South Island of New Zealand.
In 2013, the variety Acaena microphylla var. pauciglochidiata was classified as "At Risk - Naturally Uncommon" under the New Zealand Threat Classification System. By 2018, due to an actual decline, the status changed to "At Risk - Declining". (The area of occupancy had decreased to 100 km2 or less, and the predicted decline was 10 to 50%). However, the variety Acaena microphylla var. microphylla was classified as "Not Threatened" in 2004, 2009 and 2012, and again in 2018.