Chaenactis glabriuscula
Chaenactis
common yellow chaenactis, yellow pincushion
chaenactis, dusty-maidens, false-yarrow, pincushion
mostly 1–5(–12; sometimes ± horizontal);
branches proximal and, often, distal.
erect to prostrate, usually branched.
basal (often withering) and cauline, 1–10 cm;
largest blades linear or ± elliptic, plane to 3-dimensional, succulent or not, (0–)1–2-pinnately lobed;
primary lobes 1–7 pairs, remote to ± congested, ultimate lobes ± plane, involute, twisted, and/or terete.
basal and/or cauline (smaller and sparser distally except in C. cusickii); alternate; usually petiolate;
blades deltate, elliptic, linear, oblanceolate, or ovate (plane or ± 3-dimensional), (0–)1–4-pinnately (rarely -subpalmately) lobed, ultimate margins entire, faces glabrous or hairy, often stipitate-glandular or gland-dotted.
1–20(–30) cm, distally stipitate-glandular, ± villous, arachnoid-sericeous, lanuginose, and/or glabrescent.
± hemispheric to obconic or broadly cylindric.
hemispheric to obconic or broadly cylindric, (3–)5–15[–25] mm diam.
convex to ± flat, pitted and/or knobby, usually epaleate (paleae 3–10+ in C. carphoclinia).
corollas bright to dark yellow, 4–8 mm (inner);
peripheral corollas spreading, ± zygomorphic, enlarged.
0 (sometimes simulated by enlarged peripheral disc corollas).
8–70+, bisexual, fertile (diurnal with anthers exserted except in C. macrantha);
corollas white, pinkish, cream, or yellow, tubes shorter than cylindric or funnelform throats, lobes 5, deltate to ± lanceolate (sometimes enlarged, unequal; style-branch appendages blunt, obscure).
longest 4.5–10 mm;
outer stipitate-glandular, ± villous, arachnoid-sericeous, lanuginose, and/or glabrescent in fruit, apices erect, blunt, ± rigid.
5–21+ in 1–2(–3) series (subequal to unequal).
(± radiant) mostly 1–20+ per stem.
discoid or ± radiant, borne singly or in (terminal) ± cymiform arrays (erect in bud except C. macrantha).
3–9 mm (± terete);
pappi of (1–)4 scales in 1 series, or of (5–)8 scales in 2, abruptly unequal series, longest scales (1–)2–8 mm.
clavate to ± cylindric or compressed, obscurely 8–20-angled, faces scabrous and strigose to densely sericeous (usually eglandular);
pappi usually persistent, of (1–)4–20, distinct, ± erose scales in 1–4 series (equal or unequal, outer then shorter, scales usually fewer and/or shorter on peripheral cypselae, midnerves obscure), sometimes 0 or coroniform.
= ? (n = 6, 8, plus polyploids and dysploid numbers).
= 12.
Chaenactis glabriuscula
Chaenactis
Varieties 5 (5 in the flora).
The diverse and intergrading forms here included in Chaenactis glabriuscula have been divided by P. Stockwell (1940) and subsequent workers into as many as four species and ten varieties. Chaenactis glabriuscula is known from the southern two-thirds of the Californian Floristic Province and adjacent desert edges. It has been reported in Massachusetts as a garden escape (variety unspecified); it is not expected to persist there outside cultivation.
Complete interfertility among the taxa recognized here as Chaenactis glabriuscula vars. glabriuscula, megacephala, and lanosa was demonstrated by P. Stockwell (1940). Intraspecific crosses involving C. glabriuscula var. orcuttiana were much less successful; C. glabriuscula var. heterocarpha was not tested. As noted by W. J. Hooker and G. A. W. Arnott ([1830–]1841) and D. W. Kyhos (1965), some forms of C. glabriuscula differ from C. stevioides or C. fremontii only in corolla color, which can be lost in older or poorly preserved specimens.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species 18 (17 in the flora).
Chaenactis species grow in arid to alpine or Mediterranean climates, usually in open, unstable or early seral habitats (loose sand, scree, talus, shrink-swell clay, fire-adapted vegetation, recent disturbances). Some annual species have been grown in gardens in the eastern United States.
Differences in induments are key to distinguishing some Chaenactis species. Unless otherwise noted in descriptions and key leads, assume for any given plant that indument of proximal leaves and adjacent proximal portions of stems (“proximal indument”) is similar; indument of distal leaves is, likewise, similar to indument of stem portions from which they arise; peduncle indument is denser distally than proximally; and distal peduncle indument is similar to proximal phyllary indument. Unless otherwise noted, phyllary traits apply to the outer series only. Pappus scales may be equal, subequal, or unequal; unequal scales may intergrade (here said to be in gradually unequal series) or may form two, more or less uniform, shorter and longer series (here said to be in abruptly unequal series); subequal scales are said to be in subequal series. Excellent illustrations of most Chaenactis species appeared in L. Abrams and R. S. Ferris (1923–1960, vol. 4) and A. Cronquist (1955).
Section Acarphaea is distinctive by its farinose indument and base chromosome number of 8, among other traits; it could prove to be a separate, convergent genus. Natural and artificial hybrids have been documented among some members of sect. Chaenactis (see further discussion there). Reports of hybrids among species of the other two sections are few and doubtful. Chaenactis appears to be most closely related to the monotypic Dimeresia and Orochaenactis, which B. G. Baldwin et al. (2002) treated together as a narrowly circumscribed tribe, Chaenactideae.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Pappi of (5–)8 scales in 2, abruptly unequal series | var. heterocarpha |
1. Pappi of (1–)4(–5) scales in 1 series | → 2 |
2. Proximal indument whitish, ± densely lanuginose; leaves ± basal (persistent) | var. lanosa |
2. Proximal indument grayish, ± arachnoid, or glabrescent; leaves basal (withering) and cauline | → 3 |
3. Largest leaf blades succulent, mostly 2-pinnately lobed; stems ± horizontal | var. orcuttiana |
3. Largest leaf blades scarcely succulent, 1(–2)-pinnately lobed; stems ascending to erect | → 4 |
4. Longest phyllaries 7–9 × 2–3 mm, outer glabrescent in fruit; pappi: lengths of longest scales ± 0.9(–1) times corollas | var. megacephala |
4. Longest phyllaries 5–7 × 1–2 mm, outer (at least medially) ± arachnoid-sericeous and, often, ± stipitate-glandular in fruit; pappi: lengths of longest scales 0.4–0.7 times corollas | var. glabriuscula |
1. Annuals; proximal indument predominantly ± farinose, not arachnoid; largest leaf blades (2–)3–4-pinnately lobed | sect. Acarphaea |
1. Annuals, biennials, perennials, or subshrubs; proximal indument predominantly arachnoid, lanuginose, pannose, stipitate-glandular, or glabrescent, not farinose; largest leaf blades (0–)1–2-pinnately or -subpalmately lobed | → 2 |
2. Biennials, perennials, or subshrubs (rarely flowering first year); pappi of (8–)10–20 scales in 2–4 equal or gradually unequal series; leaf blades gland-dotted beneath indument | sect. Macrocarphus |
2. Annuals; pappi usually of (1–)4–8(–14) scales in 1, 2 abruptly unequal, or 2–3 gradually unequal series, sometimes 0 or coroniform; leaf blades not gland-dotted (except C. macrantha) | sect. Chaenactis |
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