Morphological, anatomical, habit, and habitat differences among the goldenaster genera Chrysopsis, Heterotheca, and Pityopsis (Compositae–Astereae)

Abstract

The leaf morphology and anatomy, fruit morphology, growth forms, and distribution patterns of species of the three goldenaster genera Chrysopsis, Heterotheca, and Pityopsis were analyzed and compared, with the conclusion that they should be treated as three distinct genera. The species of Chrysopsis were characterized by flexible flagelliform hairs. Heterotheca had stiff uniseriate, osteolate hairs. Pityopsis had long filamentous hairs that adhered to each other in a reticulate pattern. Chrysopsis and Heterotheca had similar leaf anatomy and compressed-obconic fruits (except for the epappose ray floret fruits of sect. Heterotheca). Pityopsis had distinctive leaf anatomy and morphology and had fusiform fruits. Chrysopsis included one annual plus biennial to weakly perennial and true perennial species distributed primarily in Florida. Pityopsis included only herbaceous perennials with fibrous roots distributed throughout the southeastern United States for the most part. Heterotheca included mostly herbaceous perennials with taproots distributed throughout western North America from Canada to Mexico. Some members of sect. Heterotheca were annuals occurring in the southern United States. A key to the genera and sections of the goldenasters has been included. The following new nomenclatural combinations have been made: Chrysopsis gossypina ssp. cruiseana, C. gossypina ssp. hyssopifolia, C. gossypina, f. trichophylla, Heterotheca camphorata, Pityopsis adenolepsis, and Pityopsis graminifolia var. microcephala.