Bindii

Bindii is a prostrate, mat-forming annual broadleaf weed that grows flat against the ground, rarely rising more than a centimetre or two above the turf canopy. Its leaves are finely divided and fern-like, bright to mid-green, arranged in a rosette that spreads outward from a central point. The plant has a shallow taproot and forms dense, low mats that can be hard to spot until the seed heads develop.

The inconspicuous flowers are small, greenish-yellow and sit tight against the crown of the plant at the base of the leaf rosette, largely hidden within the foliage. As these mature they form the characteristic seed cases, each bearing a hard, sharp spine. It is this spiny seed case, not the foliage, that causes the well-known injury to bare feet, paws and knees on lawns and sportsfields.

Bindii is a winter annual, germinating with autumn rains, growing through winter and setting seed in spring as temperatures rise. By late spring and into summer the parent plant dies off, leaving behind a bank of spiny seed in the thatch and soil that persists until the following autumn germination.

It is widespread across southern and temperate Australia, particularly in couch, kikuyu and buffalo lawns, sportsfields, parks and open turf areas where the sward is thin, weak or has bare patches allowing seedlings to establish. Poor turf density, low mowing height, compaction and drought stress all favour bindii establishment.

Management relies on maintaining dense, actively growing turf through appropriate mowing height, fertility and irrigation to compete against seedling establishment in autumn. Because the weed is an annual reliant on seed for survival, controlling plants before spring seed set is important to reduce the following season's population. Pre-emergent control in autumn targets germinating seedlings, while post-emergent options are most effective on young plants before the spiny seed cases have formed.