Digitalis.

Many years ago I was asked if foxglove honey was poisonous, bearing in mind that the toxicity of the rest of the plant. It is a difficult question to answer as data is difficult to come by and context is important. I suspect that the subject arose because the questioner was concerned about eating a suspect sample of honey.

There are several plants that do secret toxic nectar, the well known ones  are rhododendron and ragwort but, while some species of bumblebees thrive on them honey bees will avoid them unless they are starving. Then, of course, there is no reason why the nectar should be toxic as it exists purely as a bribe to encourage insects to pollinate the flowers, it's not a good policy to poison one's benefactors. There are many instances of parts of organisms being toxic while the rest of that organism is good to eat. There is the story of an accident prone Australian Antarctic expedition, led by Douglas Mawson in 1912, having to eat their sled dogs to survive; the consumption of dog liver proved fatal causing Vitamin A poisoning; this leads to the problem of classifying toxins. Vitamin A is a vital nutrient - in excess, a deadly poison; similarly, digitalis is, when used appropriately, a life preserving drug but an overdose can be fatal.

As an afterthought, apparently, water intoxication is a significant cause of death in endurance athletes - a thought I shall bear in mind when I compete in the annual 24 hour race in a couple of weeks time.

I have just posted yesterday's "There are no Steep Hills in  Scotland . . . . . ."