Dicoria
in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 86, plate 30. 1859.
| Taxon | Illustrator ⠉ | |
|---|---|---|
 | Parthenium hysterophorus Parthenice mollis Dicoria canescens | Linda Ann Vorobik Linda Ann Vorobik Marjorie C. Leggitt |
Annuals, perennials, or subshrubs [shrubs], 10–90+ cm. Stems erect, virgately to divaricately branched. Leaves cauline; proximally opposite (first 2–10+ pairs in early growth, Feb–Apr), otherwise alternate; petiolate; blades (3-nerved) lance-linear to lanceolate (proximal) or ± deltate or ovate to elliptic or lanceolate (distal), margins entire or toothed, faces sericeous to strigillose, sometimes with coarser, erect hairs, usually glanddotted as well. Heads disciform or discoid (then functionally staminate), in (mostly ebracteate) racemiform to paniculiform arrays [borne singly or loosely aggregated in 2s or 3s]. Involucres ± cupshaped to saucer-shaped, 3–5+ mm diam. Phyllaries persistent (outer) or tardily falling, distinct, outer (4–) 5 (–7) in 1 series, ± herbaceous, inner 0–4 (each subtending a pistillate floret), scarious to membranous (accrescent, ultimately ovate to elliptic in fruit). Receptacles convex; paleae cuneiform to linear, membranous, ± villous to hispid distally, sometimes wanting. Pistillate florets (0–) 1–4; corollas 0. Functionally staminate florets 5–15+; corollas whitish, funnelform, lobes 5, erect, reflexed, or incurved (anthers distinct or weakly coherent). Cypselae strongly obcompressed, often slightly cucullate, ± obovate to elliptic, margins corky-winged, irregularly toothed, faces smooth or warty, sometimes glanddotted; pappi 0 (cypselae often each with apical tuft of white hairs). x = 18.
Distribution
w North America, nw Mexico
Discussion
Species 2 (1 in the flora).
Traits that have been used to distinguish species and/or infraspecific taxa of dicorias in the flora (presence/absence of erect hairs on stems, shape, size, and toothing of distal leaves, size of cypselae, and relative development of inner phyllaries; A. Cronquist 1994) vary and combine so capriciously that I find no justification for recognition of more than a single, polymorphic species in the flora area.
Selected References
None.