Water Chestnut

water chestnut a name applied to three water plants of the genus Trapa, whose strangely shaped fruits each enclose a large white kernel bearing some resemblance to chestnuts.

The water chestnut best known in Europe is Trapa natans, often called caltrop or Jesuit’s nut. A caltrop, for which the Latin word is trapa, is a military device consisting of four metal spikes arranged so that, whichever way it falls, at least one spike points upwards. Caltrops were scattered in the path of charging cavalry to cripple the horses, and have been used more recently to burst car tyres. This water chestnut has a seed whose capsule bears four large spikes, one pair larger than the other. The kernel, of about the same size as an ordinary chestnut, has been eaten since prehistoric times in Europe; and in the 1st century ad Pliny described it as a staple food of the Thracians, who made it into bread. It remains in use in the regional cookery of Italy and France, e.g. in the Loire region.