Mintweed – Hyptis suaveolens
Habit: Annual herb becoming woody, growing 1-3m. Strong mint smell and tiny blue to purple flowers..
Spread: Attach to animals and people and spread by slashers and muddy tyres.
Mintweed can grow as both an annual and perennial. Mostly, it dies off in the late dry season and pops back up over the wet.
The photo above has been taken along a bush track just outside of Broome. This type of infestation is typical of mintweed. The seeds are spread along tracks via vehicles and animals and once established the plants continue to infiltrate further into the bush. People have noticed a significant increase in the density and distribution of this plant over the last ten years. Unfortunately it can be spotted in many places where stock and people have created a disturbance. For example, the SKIPA trip up the Millie Windi track in May 2008 found this plant growing along most of the roadside and camping areas.
Mintweed has tiny blue to purple flowers generally found in clusters. The seeds become enclosed in a spiny calyx. This assists them to attach to animals, people (and swags!) and machinery and disperse into new areas.
A close up of the flower. They are only up to 7mm long so I doubt you would be looking at them this closely!
When crushed or walked on the leaves give off a strong minty smell. Even prior to flowering the plants can be easily identified by this feature and their distinctive leaves. Mintweed can grow to 3m tall.