The Black Spot!

It's common to see sycamore leaves with these black 'tar spots' in the autumn. They're caused by a fungus Rhytisma acerinum and don't actually do any harm to the tree.

Most leaves have a number of spots on them but I was interested in those that carried just single spot because they reminded me of the literary device employed by RL Stevenson in his classic pirate adventure Treasure Island . In the story, a piece of paper bearing a black mark conveys to a (usually illiterate) gang member the judgement of his peers: that he has been found guilty of breaking the pirates' code and must die. In at least one case the mere sight of the sinister warning is enough to strike the recipient dead. (This is an example of the nocebo effect, the negative counterpart of the placebo.)

It appears that the Black Spot idea may be connected with the Ace of Spades which has traditionally been known as the Death card. Its potency as an omen of ill fortune is such that it was used by American soldiers in the Vietnam war as a psychological weapon. It's said that the Ace of Spades would be left on the bodies of dead NLF soldiers or even scattered in the forest to scare them away. However it seems more likely that the morale of the American troops was boosted by this belief than that the Vietnamese were spooked by it since they had little if any concept of the significance of the card. There's a very full examination of the subject here.

(I may have been feeling a little morbid because one of our two Khaki Campbell ducks was the victim of a snatch squad yesterday. The fox took her right from the yard. Her bereaved companion has been quacking plaintively all day. Foxes don't bother with warnings. )