Exotic plants available at garden centres are more of a threat to the environment than genetically modified crops, Lord May of Oxford will tell members of the Royal Society today.
In his annual presidential address, Lord May will highlight the need for the government's decision about the commercialisation of GM crops to be based on a "debate about values and beliefs" that should be held "against a realistic background of the possibilities that tomorrow's agricultural biotechnology may offer".
In the speech, which this year marks the 342nd anniversary of the society, he will caution against "fundamentalist" lobby groups that "know, by dogma, instinct or political ideology, that GM crops are bad, and the scientific facts are irrelevant".
He will describe how pollen from conventional crops - often the product of high-tech methods - can blow around to produce hybrids.
"But, far from being superweeds, these are typically wimps," he will say. "There are, however, real problems with invasive species in the UK. But they come from plants you can buy at garden centres."
Examples of these include the invasive aquatic weed Australian swamp stonecrop, or Crassula helmsii , which first "escaped" garden ponds in 1956 and now infests more than 2,000 sites; and the floating pennywort, Hydrocotyle ranunculoides , a problem in the Exminster Marshes in Devon and the Pevensey Levels in Sussex.
Today sees the launch of a review of GM crops, led by David King, the government's chief scientific adviser, and Howard Dalton, scientific adviser to the Department for Environment, Food and Rural Affairs (see above).
Professor King has written to the scientific community asking them to contribute to a "full, open, transparent and informed review" to establish the state of scientific knowledge, consensus and uncertainty.
This would be analysed by a panel of 20 experts, including scientists, representatives of commercial organisations and of pro and anti-GM groups. The inquiry should inform government decision-making.
It was one of three reviews ordered by environment secretary Margaret Beckett in May in response to recommendations by the Agriculture and Environment Biotechnology Commission. It will report next summer and will include public debate and a study of economic costs and benefits.
Earlier this month, Malcolm Grant, chair of the AEBC, warned that the reviews were underfunded and were being rushed through before the results of GM crop trials, due next year.