December in the hills with Michele Dickson and Chris Horne
Ozothamnus leptophyllus, Tauhinu, Cottonwood
Ozothamnus leptophyllus (previously described as three species of the genus Cassinia), is a common local plant belonging to the daisy family, Compositae (Asteraceae). The name tauhinu is also used for another plant, Pomaderris amoena.
Origin of the botanical name
Ozothamnus comes from the Greek words ‘ozo’ – smelly and ‘thamnus’ – shrub, referring to the musky scent of the plants; leptophyllus means ‘with slender leaves’. Tauhinu is the Te Reo name and common name.
Distribution and habitat
Ozothamnus leptophyllus is endemic to Aotearoa/ NZ. It grows on Te Ika a Māui/North Island, Te Waipounamu/South Island, Rakiura/Stewart Island and Motu Maha/the Auckland Islands. Look for it in coastal to lower montane shrublands, grassland, dunes, open areas and disturbed land. Sun-loving, it also tolerates frost and salt.
Tauhinu is a fast-growing, grey-coloured, bushy shrub up to 2 m or more high. Its weedy appearance and ability to rapidly colonise open areas has resulted in the plant’s listing in some weed books. The small, leathery leaves are up to 4 mm x 2.5 mm, linear with slightly recurved margins and are spirally arranged on the branchlets. A white or greyish tomentum of matted soft hairs covers the undersides, as it does on the many dense, slender, rough-barked branchlets.
In early spring to summer a profusion of large, cap-shaped clusters of dense flower-heads develop at the tip of branches. The tiny, round, cream or pale gold daisy flowers are papery and have a subtle perfume. One-seeded fruits are small, dry, about 1 mm long with pappus hairs up to 4 mm long at one end, which grouped together in a mature seed-head give a fuzzy look. These are wind-dispersed, germinating easily on bare soils.
Planting tauhinu has been suggested as a way to stabilise sand dunes inland of foredunes. In laboratory analysis, some plant extracts have been found to have antiviral and antifungal activity.
Where to find Ozothamnus leptophyllus?
You can see tauhinu on Wellington coastal hills, grazed hills of Terawhiti/Makara, the Parangarahu Lakes area of East Harbour Regional Park, Ōruapouanui/ Baring Head, Cape Turakirae and on grazed hills along the Skyline Walkway. Also look for tauhinu on the Aorangi, Remutaka and Tararua ranges.