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• Physical Description
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• Reproduction
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Taxonomy

Notes:

Name Status: Accepted Name. Latest taxonomic scrutiny: 15-Mar-2000

Physical Description

Genus Chaenactis:

Annuals, biennials, perennials, or subshrubs, (2-) 5-70(-200) cm (taprooted). Stems erect to prostrate, usually branched. Leaves 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. Heads discoid or ± radiant, borne singly or in (terminal) ± cymiform arrays (erect in bud except C. macrantha). Involucres hemispheric to obconic or broadly cylindric, (3-) 5-15[-25] mm diam. Phyllaries 5-21+ in 1-2(-3) series (subequal to unequal). Receptacles convex to ± flat, pitted and/or knobby, usually epaleate (paleae 3-10+ in C. carphoclinia). Ray florets 0 (sometimes simulated by enlarged peripheral disc corollas). Disc florets 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). Cypselae 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. x = ? (n = 6, 8, plus polyploids and dysploid numbers).

Species 18: w North America, nw Mexico.

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).

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 dis-cussion 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.^[1]

Habit: Forb/herb

Images:

Distribution

Range and Population

North America

Reproduction

Duration: Annual

Similar Species

Members of the genus Chaenactis:

There are approximately 70 species, subspecies, varieties, forms, and cultivars in this genus: C. achilleaefolia · C. achilleifolia · C. alpigena (Mountain Pincushion) · C. artemisiaefolia · C. artemisiifolia (Artemisia-Leaf Pincushion) · C. artimisiafolia · C. aurea · C. brachypappa · C. carphoclina · C. carphoclinia (Pebble Pincushion) · C. carphoclinia Gray var. carphoclinia Gray (Pebble Pincushion) · C. carphoclinia Gray var. peirsonii (Jeps.) Munz (Peirson's Pincushion) · C. carphoclinia var. carphoclinia · C. carphoclinia var. peirsonii · C. carphoclinia var. Rubricaulis · C. cheilanthoides · C. cinerea · C. cusickii (Cusick Pincushion) · C. denudata · C. dougalsii · C. douglasii (Douglas Dustymaiden) · C. douglasii var. alpina · C. douglasii var. alpina Gray (Alpine Dustymaiden) · C. douglasii var. douglasii · C. douglasii var. douglasii (Hook.) Hook. and Arn. (Douglas Dustymaiden) · C. ericoides · C. evermannii (Evermann's Pincushion) · C. filifolia · C. floribunda · C. fremonti · C. fremontii (Fremont's Pincushion) · C. glabriscula · C. glabriscula var. lanosa · C. glabriscula var. tenuifolia · C. glabriuscula (Common Yellow Chaenactis) · C. glabriuscula DC. var. glabriuscula DC. (Yellow Pincushion) · C. glabriuscula DC. var. lanosa (DC.) Hall (Yellow Pincushion) · C. glabriuscula DC. var. megacephala Gray (Yellow Pincushion) · C. glabriuscula var. glabriuscula · C. glabriuscula var. heterocarpha · C. glabriuscula var. lanosa · C. glabriuscula var. megacephala · C. glabriuscula var. orcuttiana · C. grabriuscula · C. grabriuscula var. lanosa · C. gracilenta · C. imbricata · C. lacera · C. leucopsis (Alpine Pincushion) · C. macrantha (Bighead Dustymaiden) · C. mainsiana · C. minuscula var. alpina · C. nevadensis (Nevada Dustymaiden) · C. nevii (John Day Pincushion) · C. paleolifera · C. parishii (Parish's Chaenactis) · C. pedicularia · C. peirsonii · C. pumila · C. rubella · C. santilinoides · C. santolinoides (Santolina Pincushion) · C. sterioides · C. stevioides (Broad-Flowered Pincushion) · C. suffrutescens (Shasta Chaenactis) · C. tanacetifolia var. heterocarpha · C. thompsoni · C. thompsonii (Thompson's Pincushion) · C. thysanocarpha · C. xantiana (Flesh-Color Pincushion)

Bibliography

• Mooring, J. S. 1965. Chromosome studies in Chaenactis and Chamaechaenactis (Compositae, Helenieae). Brittonia 17: 17-25.
• Stockwell, P. 1940. A revision of the genus Chaenactis. Contr. Dudley Herb. 3: 89-167.

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Notes

Contributors:

• Bisby, F.A., Y.R. Roskov, M.A. Ruggiero, T.M. Orrell, L.E. Paglinawan, P.W. Brewer, N. Bailly, J. van Hertum, eds (2007). Species 2000 & ITIS Catalogue of Life: 2007 Annual Checklist. Species 2000: Reading, U.K.
• Global Biodiversity Information Facility. Accessed November 19, 2007. http://www.gbif.org Mediated distribution data from 3 providers.

Data Sources:

Accessed through GBIF Data Portal November 19, 2007:

• Berkeley Natural History Museums, University and Jepson Herbaria DiGIR provider
• Oregon State University, Vascular Plant Collection
• USDA PLANTS, USDA PLANTS Database

Identifiers:

• Integrated Taxonomic Information System (ITIS) Taxonomic Serial Number (TSN): 37001
• Global Biodiversity Information Facility Taxonkey: 13743642
• Globally Unique Identifier: urn:lsid:ipni.org:names:192271-1
• Natural Heritage Network Species Identifier: PDAST200K0
• U.S.D.A. Plant Symbol: CHXA
• Zipcode Zoo Species Identifier: 29924

Footnotes:

1. James D. Morefield "Chaenactis". in Flora of North America Vol. 21 Page 5, 182, 364, 365, 366, 395, 400, 401, 402. Oxford University Press. Online at EFloras.org.