Abstract
A study of the morphological variation among herbarium specimens of Heterotheca sect. Ammodia yielded 1) data supporting the division H. oregona into four previously described varieties, and 2) the exclusion of Brewer's (golden)aster from the section and the genus. The types of Chrysopsis breweri var. multibracteata and C. gracilis were determined to be forms of Aster brickellioides and both have been assigned to Aster sect. Eucephalus. The four varieties of H. oregona were found to be distinguishable on the basis of sets of habit, leaf, and pubescence traits. Variety oregona is native to the Cascade and Coastal ranges from Washington to central California. Variety rudis occurs from extreme southern Oregon to east of Monterey, California. The range of var. compacta is similar, but does not extend into the South Coastal Range or Oregon. Variety scaberrima is found in the South Coastal Range. Putative hybrids between pairs of the four varieties have been collected occasionally where sympatric. The following are first reports of chromosome numbers: H. oregona var. oregona, 2n = 9II; H. oregona var. rudis, 2n = 9II; H. oregona var. scaberrima, 2n = 9II. One new combirnation is proposed: Heterotheca brandegei.
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