Large quantities of viscous, non-crystalline epicuticular waxes were observed on leaves of three goldenweed (Isocoma) species. Based on weights of residues from single 15-s chloroform extractions, wax on leaves of field-grown plants of the least herbicide-susceptible species, common goldenweed [I. coronopifolia (Gray) Greene], increased from 71 mg/dm2 in March to 286 mg/dm2 in October, which was two to four times greater than the amount present on other goldenweed species. Similar quantities were produced by leaves of glasshouse-grown plants, but maximum wax production occurred during summer months. The epicuticular wax of fully expanded leaves decreased with age. The amounts of epicuticular wax on individual plants growing within a field population varied by a factor of four.
