Seeds of hopelessness

By Colin Ogle

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READ IT: The warning sign at the Lindisfarne carpark.
READ IT: The warning sign at the Lindisfarne carpark.

No, I'm not extolling the tourist attractions of Lindisfarne castle or the ruined priory but, instead, noting a problem in the extensive sand dunes of the surrounding nature reserve.

Piripiri grows here. It is a plant familiar to most New Zealanders for its spherical sticking seed heads and may be more widely called 'bidibid' or 'biddy-biddy'.

It's foreign to Britain and called 'pirri-pirri' and is regarded as a serious environmental weed. It is thinly spread with a wide range.

Feathers of ground-nesting birds have been found so clogged with piripiri seed heads that the birds have starved.

The first specimen of piripiri was collected in Britain in 1901, where it is believed to have arrived on sheep's wool from New Zealand.

At Lindisfarne my wife and I saw tangled mats of piripiri among dune grasses where the adjoining beach carpark sign points at a New Zealand origin. This may be unfair to us because piripiri is native to Australia and perhaps New Zealand but it was given its formal name, Acaena novae-zelandiae, from Auckland material in 1871.

Some botanists believe it was brought to NZ accidentally from Australia. Extensive weed trials in Britain have found that piripiri cannot be controlled effectively by herbicides or hand-weeding.

Innovative ways of removing its seed - for example, by dragging a carpet across it - have not reduced its spread. Instead, reserve managers and volunteers undertake hand-removal of the seed heads in some places.

On the carpark notice there is a plea for people to remove seeds from clothing and pets before leaving. While we were at Lindisfarne a number of cars departed and no occupants made any attempt to check for seed.

To us the piripiri situation in Britain looked like too little action too late.

Few NZ native plants have become established as weeds in Britain, which is different from the large numbers which came from there to NZ. How their weed managers must regret not eradicating the very first piripiri plants found there.

Does this sound familiar? Imagine New Zealand today had our forebears eradicated, for example, the very first docks, thistles, ragwort and buttercups - all accidental imports from Britain. Or removed the first Onehunga weed and Tradescantia from South America, the first pink ragwort and veld grass from South Africa or the first Australian fireweed.

And these examples ignore the hundreds of deliberately imported plants which have escaped subsequently. As in the rest of the world, newly-establishing weeds are easier and cheaper to control, regardless of how they arrived.

- Wanganui Chronicle

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