T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Acaena novae-zelandiae (Bidibid)

Kingdom: Plantae 
Division: Magnoliophyta 
Class: Magnoliopsida 
Order: Rosales 
Family: Rosaceae 
Subfamily: Rosoideae 
Tribe: Sanguisorbeae 
Subtribe: Sanguisorbinae 
Genus: Acaena L. 
Species: Acaena novae-zelandiae
Common name: bidibid.  biddy-biddy, biddi-biddi, biddi-bid and a number of other variations. Maori name of piripiri.

A native of New Zealand and Australia. It can also be found elsewhere as an introduced species and is considered a noxious weed in some areas, such as Hawaii and California.  One plant can cover up to 4-5 square meters under ideal condition. Plants have a burr which is formed after flowering and it is beset with barbed spines which cling to the clothing of passers-by and to animals.  
Its a serious problem in the  wool of sheep

A developing burr

A mature bidibid burr

Acaena novae-zelandiae barbs

A cluster of bidibid burrs,  all the leaves have died.

Leaves of the Bidibid

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/