nostoc Nostoc commune, a mysterious food plant, whose name was invented, apparently out of the blue, by the 16th-century Swiss alchemist and medical writer Paracelsus. It is a blue-green alga, a primitive plant of the same class as seaweeds or the green slime seen on rocks and jetties when uncovered by the sea at low tide. However, nostoc also grows inland, usually on rocks or soil made damp by fresh water. Its unexpected arrival and odd, gelatinous, beaded form have earned it a place among the heterogeneous substances which are called manna. It was viewed with horror in medieval Europe, where it was thought to be the ‘stinking tawney jelly of a fallen planet, or the nocturnal solution of some plethorical and wanton star’ (Lovelock, 1972). An old British name is ‘star jelly’.
