Ledum groenlandicum and Chamaedaphne calyculata.

Abstract

Every plant has evolved to take advantage of a specific habitat. Some plants have very narrow habitat requirements and some take advantage of a wide range of ecosystems. Each habitat will exert evolutionary presure for plants to cope with the stresses that exist in that habitat. Ledum and Chamaedaphne are two species that have adapted to harsh conditions of the boreal forest and peatlands. Because of this, they have many similar adaptations. They have similar morphology, habit, distributions, tolerances to stress, etc. Yet that same evolutionary pressure necessarily says that they cannot both exist in the same place at the same time. Thus, they exhibit many differences as well. They have differing tolerances to shade and sunlight, to pH and moisture. These similarities and differences allow them to exist in slightly different habitats and, when growing together ensure that they do not out compete each other.