Acaena microphylla, the bidibid or piripiri,[4] and outside New Zealand, New Zealand-bur,[5] is a small herbaceous, prostrate perennial flowering plant in the rose family Rosaceae, native to both the North and South Islands of New Zealand.

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.

"[3] Acaena microphylla was first formally described in 1852 by Joseph Dalton Hooker.

The specific epithet microphylla derives from the Greek words, mikros (small) and phyllon (leaf), to give an adjective meaning "small-leaved".

pauciglochidiata was classified as "At Risk - Naturally Uncommon" under the New Zealand Threat Classification System.