Many weeds attack our ecosystems but one which closely resembles the native toetoe is among the most insidious.
Pampas, the prolific-seeding native of the South America, invades disturbed areas, such as cleared bush margins, burned areas and firebreaks.
It competes with and smothers other vegetation, and provides habitat for rats and mice.
Heavy infestations are radiating wind-blown seeds across Northland, Taranaki, Whanganui, Bay of Plenty and elsewhere.
Pampas threatens plantation forests and land of high conservation value, says Abigail Monteith, partnerships ranger for DoC's Northland District.
"It can reach distant open spaces quickly and to blanket them with very rapid growth. Some areas, such as native turfland communities, can be quickly overcome by the invasion of pampas."
Unlike the pampas, the less fluffy and more graceful toetoe has a right to be here.
The toetoe is part of this country's heritage.
Maori once used its leaves to make baskets, kites, mats, wall linings and roof thatching.
It was also used to make containers to cook food in hot springs and on the East Coast children apparently used the stalks as light spears, or "practice spears" for a play version of a more dangerous adult game.
The flower stalks were also useful - as frames for kites, and in tukutuku panelling. The seed heads themselves were used on fresh wounds to stop bleeding. Other medicinal uses included treatment of diarrhoea, kidney complaints, and burns. Toetoe is New Zealand's largest native grass, growing in clumps up to 3m in height.
Know the difference
How do you tell the difference between the exotic weed pampas and native toetoe?
The first guideline is prevalence and "promiscuity", says says plant expert Susie Longdell.
If a plant that looks like pampas or toetoe suddenly starts growing in your garden, it will very likely be a pampas from windblown or previously dormant seed.
If you come across a group of such plants they're highly likely to be pampas, unless in an obviously planned planting of native plants.
Pampas leaves snap readily when given a sharp tug. Toetoe leaves do not snap readily.
And come flowering time the difference gets easier to spot.
The two kinds of pampas prevalent in the North Island - South American natives, cortaderia selloana and C jubata - flower in late summer and autumn on tall stiffly erect flower stems.
The overall effect is like those fluffy dusters mounted on wooden rods.
Usually the masses of flowers create a fluffy or feathery off-white effect as on C selloana but can have a mauve, pinkish or purplish tinge as on the less common but still very invasive C jubata.
Both plants produce enormous quantities of seed, which can be spread by wind, water and machinery. They will also grow from small tillers broken away from larger clumps.
Our native toetoe species are more graceful in flower and much less promiscuous in spreading.
Toetoe do vary also in that they flower in spring and summer.
Cortaderia fulvida, the mountain toetoe, perhaps the most popular native species with gardeners, has drooping tawny coloured flower heads in early summer. At times, you see it growing naturally on streamsides and roadsides.
The North Island and South Island toetoe have more erect flower stems but the overall effect is still not as "soldier stiff" as those of pampas, because the flower parts attached to the central flower stem still droop gracefully.
They are also more of a golden creamy colour rather than the off-white or mauve-tinged colour of pampas.
Killing pampas grass
Small pampas plants can be dug or pulled out by hand.
Gallant (grass specific) is a commonly used herbicide for larger infestations, and Roundup is also suitable. These herbicides are best applied from spring to autumn, at label rates during calm fine weather.
Native toetoe, harakeke (flax) and gossamer grass are fantastic replacement plants. Put them in soon after the pampas control to shade out any new seedlings that sprout