An ecologist investigated the leaf length of stinging nettle (Urtica dioica) plants growing in two different habitats: near an agricultural run-off ditch (high nitrogen soil) and in an undisturbed woodland (low nitrogen soil).

The ecologist measured the maximum leaf length on twelve plants from each habitat.

The ecologist always measured the leaf from the fourth node counting down from the apical meristem (the growing tip) of the main stem.