Asteraceae (tribe Heliantheae) subtribe Chaenactidinae
(synonym of Asteraceae tribe Heliantheae subtribe Chaenactidinae)
Chaenactis
chaenactis, dusty-maidens, false-yarrow, pincushion
erect to prostrate, usually branched.
basal, basal and cauline, or cauline; opposite or alternate; usually petiolate, sometimes sessile;
blades mostly cordate, deltate, elliptic, lanceolate, linear, oblanceolate, oblong, obovate, ovate, rhombic, or spatulate, often 1–2-pinnately or -ternately lobed (lobes mostly filiform to linear, lanceolate, or oblanceolate), ultimate margins entire or toothed, faces ± lanate to woolly, or hispidulous to scabrellous or strigose, sometimes glabrescent, sometimes stipitate-glandular, rarely glabrous, often gland-dotted.
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.
campanulate to narrowly cylindric or obconic, or hemispheric to rotate.
hemispheric to obconic or broadly cylindric, (3–)5–15[–25] mm diam.
conic, flat, or hemispheric, often knobby or pitted (sometimes hairy or gland-dotted), usually epaleate (paleae sometimes subulate scales in Chaenactis; in Bartlettia, linear, membranous, hairy scales, each appressed to and shed with an associated cypsela may be interpreted as paleae).
convex to ± flat, pitted and/or knobby, usually epaleate (paleae 3–10+ in C. carphoclinia).
0 (corollas of peripheral florets sometimes notably larger than those of the inner, then zygomorphic, showy, and somewhat raylike, e.g., Chaenactis spp.) or (1–)4–21(–60+), pistillate, fertile;
corollas yellow, orange, red, purplish, or whitish (persistent, marcescent in Arnica dealbata).
0 (sometimes simulated by enlarged peripheral disc corollas).
4–200+, usually bisexual, fertile (functionally staminate in Arnica dealbata);
corollas yellow, orange, purplish, or whitish, usually hairy and/or gland-dotted or stipitate-glandular, tubes shorter than to longer than cylindric or campanulate to funnelform throats, lobes 5, deltate to linear;
anther thecae pale;
stigmatic papillae in 2 lines.
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).
usually persistent, 4–60+ in 1–4+ series (usually erect at flowering, usually reflexed in fruit, usually distinct, basally coherent in some Arnica spp., mostly lance-ovate, linear, or ovate, unequal to subequal, mostly herbaceous to membranous, outer foliaceous in Venegasia).
5–21+ in 1–2(–3) series (subequal to unequal).
usually 0 (sometimes 1–3 bractlets in Schkuhria).
usually radiate, sometimes discoid, rarely radiant (Chaenactis spp.), borne singly, or in clusters, or in corymbiform, cymiform, or paniculiform arrays.
discoid or ± radiant, borne singly or in (terminal) ± cymiform arrays (erect in bud except C. macrantha).
mostly obpyramidal and 4–5-angled, sometimes clavate, columnar, cylindric, or fusiform, sometimes compressed and ± linear (e.g., Chaenactis, Hulsea) or obcompressed (e.g., Arnica dealbata, Bartlettia; lengths usually 3+ times diams.), faces usually hairy and/or gland-dotted;
pappi falling, fragile, or persistent, usually of 6–80 distinct or basally connate bristles, or of 4–20 distinct (or basally connate) scales, all, some, or none aristate, sometimes pappi none.
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).
Asteraceae (tribe Heliantheae) subtribe Chaenactidinae
Chaenactis
Genera 25, species 129 (19 genera, 83 species in the flora).
The circumscription of Chaenactidinae used here (that of H. Robinson 1981) contrasts sharply with that of B. G. Baldwin (Baldwin and B. L. Wessa 2000; Baldwin et al. 2002). Baldwin included Chaenactis, Dimeresia (here segregated in Dimeresiinae), and Orochaenactis in his Chaenactidinae (as sole subtribe in his Chaenactideae) and placed other genera of Chaenactidinae in the sense of Robinson as follows: Amauriopsis, Bahia, Bartlettia, Chamaechaenactis, Florestina, Hymenothrix, Palafoxia, Peucephyllum, Picradeniopsis, Platyschkuhria, Psathyrotopsis, and Schkuhria in Bahiinae (in Bahieae); Arnica in Arnicinae (in Madieae); Hulsea in Hulseinae (in Madieae); Syntrichopappus in Baeriinae (in Madieae); Venegasia in Venegasiinae (in Madieae); and Jamesianthus in Pectidinae (in Tageteae).
(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 wholly or partially of bristles (pappi 0 and ray corollas whitish with red veins in Syntrichopappus lemmonii) | → 2 |
1. Pappi none or wholly of scales (all, some, or no scales aristate) | → 7 |
2. Leaves all or mostly opposite | → 3 |
2. Leaves mostly alternate (sometimes mostly basal) | → 4 |
3. Phyllaries 8–23 in (1–)2 series (subequal); pappi persistent, of 10–50 bristles | Arnica |
3. Phyllaries 14–18+ in ± 3 series (unequal); pappi fragile, of 6–8+ bristles | Jamesianthus |
4. Shrubs or treelets; leaf blades linear-filiform | Peucephyllum |
4. Annuals or perennials; leaf blades mostly deltate, elliptic, or rhombic | → 5 |
5. Cypselae obcompressed (each shed together with a subtending, linear, membranous scale, margins ciliate) | Bartlettia |
5. Cypselae clavate, fusiform, obconic, or obpyramidal (margins not ciliate) | → 6 |
6. Ray florets 5–8; pappi 0, or ± fragile (falling in whole of fragmented rings), of 25–40 basally connate or coherent bristles in 1–2 series | Syntrichopappus |
6. Ray florets 0; pappi persistent, of 70–90 distinct, unequal bristles in 2–3series | Psathyrotopsis |
7. Leaves all or mostly cauline, usually all or mostly opposite (distal sometimes, usually in Bahia, alternate) | → 8 |
7. Leaves all or mostly basal, or mostly cauline, mostly alternate (proximal sometimes opposite) | → 11 |
8. Leaves woolly; rays 5–12 (corollas persistent, marcescent); disc florets usually functionally staminate; cypselae obovoid or plumply fusiform, smooth or ca. 20-ribbed | Arnica |
8. Leaves usually ± hairy (not woolly, hairs white, straight, often bulbous, conic, or fusiform, 0.1–0.8 mm), sometimes glabrous, sometimes stipitate-glandular, usually gland-dotted; rays 0, or 1–15 (corollas withering, not marcescent); disc florets bisexual, fertile; cypselae obpyramidal, mostly 4-angled | → 9 |
9. Phyllaries 4–9(–12, margins often purplish or yellowish) | Schkuhria |
9. Phyllaries 6–18+ (margins rarely purplish, not yellowish) | → 10 |
10. Annuals, biennials, or perennials, 10–80+ cm; leaves all or mostly opposite (if perennials, blades lanceolate to oblong, 2–20+ mm wide), or all ormostly alternate | Bahia |
10. Perennials, 3–20+ cm; leaves all or mostly opposite (blades or lobes lanceolate to lance-linear, mostly 1–8 mm wide) | Picradeniopsis |
11. Phyllaries 20–40+ in 3–4+ series (unequal, outer spreading or reflexed at flowering, rotund to broadly ovate, foliaceous) | Venegasia |
11. Phyllaries mostly 4–21(–60+ in Hulsea; subequal to unequal, all ± erect at flowering, mostly lanceolate, linear, oblanceolate, obovate, or spatulate, not foliaceous) | → 12 |
12. Disc corolla lobes lance-linear, lance-oblong, or linear (lengths mostly 2+ times widths) | → 13 |
12. Disc corolla lobes mostly deltate, lance-deltate, lanceolate, or ovate (lengths mostly 1–2 times widths, sometimes longer in zygomorphic corollas of some Chaenactis spp.) | → 15 |
13. Pappus scales 12–18 | Hymenothrix |
13. Pappus scales 4–12 | → 14 |
14. Leaf blades broadly lanceolate to linear (not lobed); corollas usually pinkish or purplish, sometimes whitish; cypselae densely to sparsely hairy (hairs straight) | Palafoxia |
14. Leaf blades (at least mid-cauline) 3- or 5-lobed or -foliolate (blades or leaflets broadly to narrowly oblong to ovate); corollas whitish; cypselae sparsely hairy (hairs curled) | Florestina |
15. Leaves sparsely to densely hirtellous, scabrellous, or strigose (hairs white, straight, often conic or fusiform, 0.1–0.8 mm), sometimes glabrescent, sometimes stipitate-glandular, usually gland-dotted; cypselae obpyramidal, 4-angled | → 16 |
15. Leaves mostly sparsely lanate, tomentose, or woolly (hairs crisped, tangled or matted, mostly 0.8+ mm), sometimes glabrescent, or finely granular-pubescent (hairs bulbous, less than 0.2 mm), or glabrous, sometimes stipitate-glandular or gland-dotted; cypselae clavate, ± cylindric, or obconic, often compressed and ± linear, obscurely, if at all, 4-angled (sometimes obscurely 8–20-angled) | → 18 |
16. Leaves mostly cauline, blades deltate, oblong, or ovate overall, usually 1–2-ternately lobed | Amauriopsis |
16. Leaves mostly basal or basal and cauline, blades cordate, elliptic, lanceolate, ovate or rounded | → 17 |
17. Plants mostly 10–50+ cm; leaf blades mostly lanceolate, sometimes ± ovate; heads borne singly or in corymbiform to paniculiformarrays; rays 6–12 | Platyschkuhria |
17. Plants 2–7(–9) cm (10–20+ cm across); leaf blades cordate, elliptic,ovate, or rounded; heads borne singly; rays 0 | Chamaechaenactis |
18. Ray florets 9–60+ | Hulsea |
18. Ray florets 0 (corollas of peripheral florets sometimes zygomorphic and larger than inner, heads radiant) | → 19 |
19. Heads borne singly or in ± cymiform arrays; disc florets 8–70+ | Chaenactis |
19. Heads borne singly or (2–5) in clusters (at stem tips); disc florets 4–9 | Orochaenactis |
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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