The History of the World in 100 Plants by Simon Barnes

Author:Simon Barnes
Language: eng
Format: epub
Publisher: Simon & Schuster UK
Published: 2022-10-27T00:00:00+00:00

FIFTY-TWO JAPANESE KNOTWEED

‘Would you like foreigners to come into your house, settle down and help themselves to your fridge?’

Jean-Louis Debré, French interior minister, 1997

Accounts of invasive plants always sound like science fiction: as if the plants were the creation of an evil genius or the emanation of a hideous force from a distant galaxy. The success of an invasive species seems both inevitable and a moral judgement on humankind. The fact is that despite the success of kudzu (Chapter 35), it’s hard for any plant to establish itself in an alien environment. For a start there are, more or less by definition, very few of them in the new place, so the plant has nothing in reserve and few opportunities for sexual reproduction. There’s a rough rule of 10 per cent: only about 10 per cent of plants that find themselves in an alien environment survive in the wild without human help. Of these, only about 10 per cent establish themselves as viable species. The process can be seen as the most searching possible examination of a plant’s reproductive strategy.

An alien does start with certain advantages. There are no natural predators: no animals, fungi or plant parasites that have evolved to exploit the plant. There are no indigenous diseases to keep it in check. Nothing in the new environment has an ecological niche based on the damage it can do to any alien plant: it would be a contradiction. But that works the other way: there is nothing there to help it either: no natural pollinators, no natural dispersers of seeds. The conditions of the new country are unlikely to fit the plant’s natural requirements in terms of temperature, moisture, soil type and seasonal rhythm. A successful invasive plant needs toughness and the ability to operate as something of a generalist. A specialist that has perfectly evolved for one type of environment is unlikely to be able to transport those skills to another. The all-rounder has a better chance.

Japanese knotweed fits that description pretty well, and it has become a serious problem in Europe and North America. It joins a long list. The Royal Botanic Gardens at Kew calculates that 6,075 global species of plants are invasive. Some of them are of minor significance, but others have had a dramatic effect on their new environment: as well as kudzu, there are problems with giant hogweed, Himalayan balsam, rhododendron, New Zealand pygmy weed, purple loosestrife, Norway maple, English ivy (in America), caulerpa seaweed, water hyacinth, tamarisk and many others. In Hawaii, the invading miconias are attacked with a paintball gun from a helicopter, the pellets full of herbicide. Koster’s curse is an invasive bush now found in many tropical regions outside its Central American home range.

Not such a challenge: cartoon by Glenn Marshall.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.