Spinyhead sida (Sida acuta)
Spinyhead sida flower
Spinyhead sida is declared a Class B (growth and spread to be controlled) and Class C (not to be introduced to the Northern Territory) weed in accordance with the NT Weeds Management Act 2001.
- Spinyhead Sida Photo Identification Table (pdf 121Kb)
Spinyhead sida is an invasive unpalatable shrub that competes with and excludes native plants as well as pasture and crop species. Spinyhead sida can infest areas where degraded, disturbed and improved soils occur. Prolific seeding has contributed to spinyhead sida becoming a common weed of road verges, camp grounds, and other areas where soils have been disturbed and or degraded. Spinyhead sida will also invade native and improved pastures as well as crops and domestic gardens.
The seeds adhere to fur, clothing and other fibrous materials making it easy to spread. Seeds also spread as impurities in agricultural produce such as hay and pasture seed, as well as on hooves, footwear and vehicles. Spinyhead sida seeds are able to germinate even after being eaten by stock and passing through their digestive systems. Sida seeds can persist for elongated periods of time; seedlings may appear years after the successful removal of mature plants.
A native of Central America, spinyhead sida has spread throughout the tropics and sub-tropics in the Pacific, Asia and Australia. In Australia, spinyhead sida is widespread in the higher rainfall areas from Brisbane in Queensland to the Ord River region of Western Australia. In the Northern Territory (NT) it is common in the Darwin, Katherine, Gulf and Victoria River regions.
Spinyhead sida is found on most soil types except some of those derived from limestone and seasonally flooded clays. In agricultural areas, infestations can become established in high traffic areas such as lane ways, around troughs and cattle yards.
Spinyhead sida
