Acacia Koa Leaves and Phyllodes: Gas Exchange, Morphological, Anatomical, and Biochemical Characteristics

Abstract

Acacia koa Gray has two leaf forms: (1) the horizontal, bipinnately compound "true leaves," and (2) the vertical phyllodes, flattened petioles, that are parallel to overhead radiation. Leaves are morphologically and anatomically distinct from phyllodes. Photosynthetic characteristics such as light saturation point, light compensation point, and CO2-compensation concentration of the two leaf forms are similar. Leaves contain substantially more total protein and ribulose bisphosphate carboxylase than phyllodes. By area, phyllodes contain more chlorophyll than leaves, but by weight, leaves contain more than phyllodes. Leaves and phyllodes have similar dark respiration rates. The rate of transpiration of phyllodes is greater than that of leaves, but total leaf conductance is about the same for both leaf forms.