in A. P. de Candolle and A. L. P. P. de Candolle, Prodr.5: 310. 1836
United States, n Mexico.
Species 4 (4 in the flora).
Aphanostephus is distinguished from other white-rayed Astereae by its combination of ovate-lanceolate, scarious-margined phyllaries, conic receptacles, usually thick-ribbed, columnar, 4-angled cypselae often bearing duplex hairs with coiled or recurved apices, reduced pappi, and low chromosome number(s). B. L. Turner (1984) emphasized characters of achenial vestiture and chromosome numbers to reduce the number of species from the 11 recognized by L. H. Shinners (1946). Cypsela hairs must be examined with a dissecting microscope to determine their morphology. Leaves may be highly variable in size, shape, and insertion within species, from 15–50 mm, entire to deeply lobed or pinnatifid, and non-clasping to clasping or subclasping.
Aphanostephus was hypothesized to be closely related to Townsendia, Astranthium, and a group of Southern Hemisphere genera (subtribe Brachyscominae) on the basis of various morphologic features (G. L. Nesom 1994). In contrast, molecular data (D. R. Morgan 1990; M. A. Lane et al. 1996; R. D. Noyes 2000; Noyes and L. H. Rieseberg 1999) indicate that Aphanostephus has arisen from within the Conyzinae, apparently as the sister group to the E. bellioides de Candolle group of Erigeron.
Elisens, W. J., R. D. Boyd, and A. D. Wolfe. 1992. Genetic and morphological divergence among varieties of Aphanostephus skirrhobasis (Asteraceae–Astereae) and related species with different chromosome numbers. Syst. Bot. 17: 380–394.
|1||Cypsela hairs either 1-directionally apically coiled or glochidiate (cells abruptly reflexed in opposite directions, forming prong); annuals or perennials||> 2|
|1||Cypsela hairs apically straight; annuals||> 3|
|2||Annuals; bases of disc corollas bulbous-swollen (mature); cypsela hairs apically 1-directionally coiled; pappi usually coroniform, uneven, rarely of acute to awn-tipped scales 0.2–2 mm||Aphanostephus skirrhobasis|
|2||Perennials; bases of disc corollas not conspicuously swollen; cypsela hairs apically glochidiate; pappi coroniform, minutely ciliate or lacerate, 0.1–0.3 mm||Aphanostephus riddellii|
|3||Vestiture sparsely hispido-pilose, stem hairs spreading at right angles, thick-based, straight, 0.6–2.4 mm; ray florets 13–21||Aphanostephus pilosus|
|3||Vestiture puberulent, stem hairs spreading to deflexed, thin-based, 0.2–0.6 mm; ray florets 26–35||Aphanostephus ramosissimus|
|Author||Guy L. Nesom +|
|Common name||Lazydaisy +|
|Etymology||Greek aphanes, obscure, and stephanos, crown, apparently alluding to low coronal pappus of some species +|
|Illustrator||Barbara Alongi +|
|Reference||elisens1992a +, shinners1946d + and turner1984a +|
|Synonym||Keerlia de +|
|Taxon name||Aphanostephus +|
|Taxon parent||Asteraceae tribe Astereae +|
|Taxon rank||genus +|
|Volume||Volume 20 +|