Paul Lewis: New Zealand natives are keeping a firm grip on San Francisco soil

Pohutukawa are doing rather too well in San Francisco.

Team New Zealand aren't the only New Zealand natives creating waves in San Francisco - so are the pohutukawa.

It was with some shock that a recent bike trip to work during the America's Cup was halted by the entirely unexpected sight of a pohutukawa in San Francisco's Bay St. It is in a small stand there, part of thousands imported and planted in San Francisco during the 1980s. It was like seeing Lake Taupo in Australia's Nullarbor Plain.

However, the humble pohutukawa have been doing well in San Francisco. They are doing so well that their insistent root structure is causing damage to paths, kerbs, sewers and drains.

It turns out San Francisco is all too familiar with the tree they call the New Zealand Christmas tree. About three years ago, a local woman had had enough of the lovely tree planted about 26 years earlier.

It had buckled the footpath and so interfered with her sewers that it caused 17 blockages in 10 years. She fought a battle with the local council, culminating in a "tree trial", where (after vigorous defence from the Department of Urban Forestry) she was allowed to take the tree down.

They protect their trees here rather like our local bodies in New Zealand do but the pohutukawa are running out of friends, according to one local admirer, Dr Laurence Costello, an environmental horticulture adviser to the University of California for many years (now retired) and a private consultant.

"They are regarded as a mistake now," said Dr Costello. "But the city is pretty much existing with the status quo - typically, just fixing the infrastructure as the damage gets caused. They will just wait until they die out."

They might have a long wait for the pohutukawa to relax their grip. The trees can live for hundreds of years, although an intensely urban environment is likely to shorten their lives.

Dr Costello said: "They are just not a street tree, that's all. It was the wrong choice. Everyone likes the tree and I think they're great - but they have such a strong root mass that they cause a lot of trouble in an urban setting.

"I was lucky enough to be in New Zealand a while back and saw them growing in their natural state in beaches, parks and along the coast."

It's good to know that, if Team NZ take the America's Cup, something of New Zealand will be left behind.