The British staple, the potato, is a fixture in meals from Sunday roasts to late-night takeaways, but Spanish food expert Pablo Ojeda has issued a stark warning about when this versatile vegetable should be discarded.

"When the flower has already come out, throw it away," he advised.

While a sprouting spud isn't uncommon, Ojeda cautions that potatoes can become dangerously toxic under certain conditions.

"When it sprouts a little bit, I'll accept it," he said during an appearance on the Spanish TV show Más Vale Tarde, "But when it has already bloomed like a flower, throw it away."

The danger lies in the potato plant's ability to produce small green fruits resembling cherry tomatoes, which contain the poisonous chemical solanine. Even if you spot stems, simply removing them isn't safe; the entire potato is contaminated and should never be consumed.

Despite their nutritional benefits, potato flowers are high in solanine and can cause serious illness – after all, they belong to the same family as the deadly nightshade.

The potato vine is also harmful to humans. Consuming the vine can lead to vomiting and diarrhoea, while even skin contact can result in redness, itching, and swelling.

Gardeners are advised to remove any flowers from their potato plants, not only because they can be toxic if ingested by small children or pets, but also because pruning will redirect the plant's energy into its tubers – the part we actually consume.

Proper storage of potatoes is crucial as well.

Decaying potatoes can release their solanine into the air, and in a poorly ventilated environment like a root cellar, inhaling this chemical could cause serious illness.