There is a native and an introduced species.
Family: Urticaceae (Nettle family).
Occurrence: Stinging Nettle is a common weed of waste areas and overgrazed farmland.
Stinging Nettle is an annual. Stinging Nettles are sometimes used as a vegetable. Cooking is said to render the stings harmless.
Scrub Nettle is a perennial. It has toothed, lanceolate leaves (i.e. the leaves are longer than wide, and taper towards the tip) which are up to 10 cm long. The male and female flowers are on separate plants (or sometimes, on separate flower clusters on the one plant). It grows to a small shrub.
Photo 1 left: Stinging Nettle. Vaughan Springs. 2: Stinging Nettle. Frederick St, Castlemaine. 3: Stinging Nettle showing the small white flowers and toothed leaves. The leaves are about as wide as long. Ballarat.