A ground cover with a secret weapon. Acaena novae-zelandiae is known as piripiri. It is a low, creeping plant. It covers the ground in open areas. The leaves are fern-like. They are divided into small leaflets. The flowers are small, greenish, inconspicuous. Then come the burrs. The fruit is a small, hard nutlet surrounded by a spiny husk. The spines are barbed. They are like tiny fishhooks. They catch on fur. On feathers. On socks. The burr is a hitchhiker. It travels with the animal that brushes against it. It falls off somewhere else. The plant spreads. Piripiri is the Māori name. It refers to the burr. Other Acaena species have similar burrs. They are all piripiri. The plant is a ground cover. It forms dense mats. It suppresses other plants. It can be aggressive. It can be a weed. But it is native. It belongs here. Acaena novae-zelandiae grows in grasslands, open forests, and disturbed areas. It is common in the South Island high country. It grows on roadsides. It grows on riverbeds. It grows where other plants struggle. The leaves are dark green. Sometimes they are bronze in winter. They are tough. They persist. The plant is evergreen. The burrs are a nuisance to walkers. They stick to socks. They stick to laces. They are hard to remove. The plant does not apologise. In traditional use, piripiri had medicinal properties. The leaves were used for skin conditions. The plant was known for its astringent qualities. Acaena novae-zelandiae is not threatened. It is common. It is widespread. It is successful. The burrs have helped it spread. The species name novae-zelandiae means "of New Zealand". The plant is named for its home. The burrs are named for no one. Piripiri is a reminder. Native plants can be annoying. They can be aggressive. They can be successful. They do not need to be rare to be valued. No significant threats exist. It may be considered a weed in some contexts but is native and valued. Common and widespread throughout New Zealand. Not threatened. Often forms extensive mats in open areas.