While making the tea the other night I idly wondered how much green potato you would have to eat to get solanine poisoning. Potatoes are in the nightshade family (look at the flowers – similar to tomato flowers, above) and I am sure I once read that if they were introduced now they would not be approved as a food plant. According to a swift web-trawl , the answer is, apparently, not all that much. Solanine develops due to the action of light on potatoes but the green colour that the potato skin becomes is down to chlorophyll rather than the toxic glycoalkaloid. So although the two things are related, the green-ness is no absolute indicator of how much solanine is present. Solanine is part of the plant’s defence against pests and apparently commercial varieties are screened to minimise human consumption. And since the lethal dose is around 5mg for each kg body weight, green potatoes are best avoided as the alternatives can include diarrhoea, vomiting, dizziness, hallucinations, paralysi...