Cores thrown from cars endanger apples

Scientists find roads lined with domesticated apple trees that are progressively hybridising native varieties

Apple cores thrown out of car windows could be endangering Britain’s last wild apple trees, researchers from the Royal Botanic Gardens Edinburgh have warned. Trees grown from cultivated supermarket apple varieties have been discovered on motorway verges, threatening Britain’s last wild apple variety, the crab apple. In some areas, more than half of crab apple trees are now hybrids, after cross-pollinating with domesticated varieties.

THROWING apple cores out of car windows could be destroying Britain’s last wild apple trees, experts warned.

Researchers from the Royal Botanic

Gardens Edinburgh discovered trees that have sprouted from supermarket varieties growing on motorway verges.

Genetic studies of crab apple trees – our last wild variety – show that in some areas more than half are now hybrids, after cross-pollinating with domesticated varieties.

Dr Markus Ruhsam, a molecular biologist at the Royal Botanic Gardens Edinburgh, who carried out the study on wild apples, said: “I wouldn’t want to discourage people from planting apple trees in their gardens. What I would like to discourage is people randomly planting apple trees in the wild.

“We want to keep wild apples wild. Another thing is not chucking your apple core out of the window. I’m guilty of it as well. But when I was looking for apple trees I suddenly realised how many there are growing along motorways and busy roads. And they are all cultivated apples.”

The crab apple, Malus sylvestris, is an ancestor to thousands of cultivated apples. It can live for 100 years, and grows to around 32ft in height, often in gnarled and twisted formations. Its intertwining branches led to it being considered a symbol of fertility and associated with love and marriage.

The crab apple was once a popular eating variety, particularly in Elizabethan England, but today is generally considered too bitter, and tends to be kept for jams, jellies and chutneys. Its trees still provide food and shelter for animals and plants.

Dr Ruhsam surveyed the genetic make-up of apple trees growing in Scotland and discovered that half of those in the central belt were hybrids. Overall, around 30 per cent of wild trees that looked pure were hybrids.

Nowhere was found to have entirely wild trees, but researchers discovered that in areas where ancient woodland was more common, including in the southern Highlands, parts of Dumfries & Galloway and the Lake District, up to nine in 10 crab apple trees were pure.

As well as discarded apple cores, amateur orchard growers have had an impact on the wild apple, as their trees cross-pollinate with native ones nearby to create hybrids. Rick Worrell, a forestry consultant who initiated the research with the support of Forestry Scotland, said: “This story is similar in some ways to that of the Scottish wild cat, under threat from hybridisation with domestic cats.

“If we are not careful, the wild apple, one of the UK’S rarer native trees, may be progressively hybridised out of existence.”

The Royal Botanic Gardens is now helping to create an orchard of 120 Dna-tested, pure-bred wild apples.