A pensioner from Exmouth has unwittingly grown a 5ft (1.5m) tall cannabis plant from a pack of bird seeds.
Patricia Hewitson, from Exmouth, contacted BBC Radio Devon's gardening programme asking for help identifying "a weed".
After discovering it was an illegal cannabis plant the police were involved.
Officers said Mrs Hewitson was growing the plant illegally but in good faith.
Mrs Hewitson said: "I sent a picture in via email and I got a couple of interesting emails back, including one from the police.
"They said they wouldn't prosecute me as I'd done it in good faith."
BBC Radio Devon's gardening expert, Sarah Chesters, said: "I think the seed of this came from the bird feeder which hangs just above their door.
"It's quite common for bird seed to contain a huge variety of plant seed and cannabis has been known to come up from it."
Cannabis is illegal to grow without a licence so Mrs Hewitson and her husband John were advised by Devon and Cornwall Police about what to do with the specimen.
"We've been told we have to cut it up and either compost it, take it to the police station or take it up to the local recycling centre," Mrs Hewitson said.
Sgt Ryan Canning, from Devon and Cornwall Police, said: "If you come into possession of an illegal drug such as cannabis, you must either destroy it or take it to a police officer.
"The lady has committed an offence although there are mitigating circumstances so we would not look to take it further although we would take it away."