Seedling emergence of broom snakeweed [Gutierrezia sarothrae (Pursh) Britt. & Rusby], threadleaf snakeweed [G. microcephala (DC.) Gray], common goldenweed [Isocoma coronopifolia (Gray) Greene], and false broomweed (Ericameria austrotexana M.C. Johnston) was studied in the glasshouse. Germination of these species is known to be light-stimulated. Seed of all four subshrubs germinated readily if placed on the surface or partially pressed into the soil. Emergence was reduced by covering seed with soil to a depth of less than 1 mm. Few seedlings emerged from a depth of 1 cm, and none emerged from a depth of 2 cm. Rate of emergence also decreased with increasing depth of placement. Soil texture had little effect on emergence. Rapid germination on the soil surface is consistent with other aspects of the regenerative strategy of common goldenweed and false broomweed, which do not depend upon a buried seed bank for regeneration. Seed burial probably provides a form of enforced dormancy in the small, long-lived seeds of the two snakeweed species.

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.