Phenology ofChrysothamnus viscidiflorussubspeciesviscidiflorus(Hook.) Nutt.

Abstract

The configuration of the growth pattern forChrysothamnus viscidiflorus(Hook.) Nutt. was determined from vegetative bud burst to flowering. Important portions of the pattern are: restrictive growth during early spring, accelerated growth in late spring when the optimum susceptibility to herbicides occurs, and a leveling off of growth before flowering. Seedlings and young plants have a more rapid and greater annual stem elongation than mature or senescent plants. Elongation during the accelerated growth period can be predicted from early spring growth with moderate precision when soil moisture and temperatures are not limiting. Populations growing on sites of higher or lower elevations or of pronounced aspect will have growth patterns moderately varying from the modal populations. The greatest factor influencing the growth pattern on years with adequate soil moisture was competition from other species and the combination of competition and age of the rabbitbrush plants.