LEAF MOTTLING - RELATION TO GROWTH FORM AND LEAF PHENOLOGY AND POSSIBLE ROLE AS CAMOUFLAGE

Proposes that mottling may serve to camouflage the foliage of certain groups of short-statured forest herbs, by disrupting their outline as perceived by colour-blind vertebrate herbivores in sun-dappled understoreys. Certain phenological groups are likely to be particularly vulnerable to herbivores, based on their high leaf N content (spring ephemerals, spring leaves of summer-active species), leaf activity when few other species possess foliage (evergreen species, wintergreen species, winter leaves of dimorphic species) and/or relative cost of replacing consumed foliage (evergreen species on sterile soils). These groups are also exposed to relatively high irradiance and so are less likely to suffer photosynthetic losses as a result of the reduced leaf absorptance that accompanies mottling. A survey of the incidence of leaf mottling in the native flora of the NE USA supports these ideas: mottled leaves occur almost exclusively among forest herbs and are substantially over-represented among evergreen, wintergreen, and spring ephemeral species, and among the winter leaves of dimorphic species and the spring leaves of summer-active species. -from Author