Prickly Lettuce, A Compass Plant

2012-11-13

Prickly lettuce is known to some of its navigating friends as the 'compass plant' and to its Roman friends as 'lactuca serriola'. In truth it is only one of many plants with the compass plant nickname (Silphium laciniatum in the US is another one), but it has earned it. In open ground, the leaves of the main stem are aligned north-south, offering the least surface area to the midday sun, but the maximum area to the weaker light of the start and end of the day. (This is a similar logic to the N-S alignment…