Artemisia bigelovii |
Artemisia subg. Tridentatae |
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Bigelow sage, Bigelow sagebrush, Bigelow sagewort, Bigelow's sage |
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Habit | Shrubs, 20–40(–60) cm (branched from bases, rounded), mildly aromatic; not root-sprouting. | Shrubs; fibrous rooted, caudices woody, rhizomes absent. | ||||||||||||||||||||||||||||||||||||||||
Stems | silvery, canescent (bark gray-brown). |
not wandlike (relatively numerous; new stems may sprout from caudices). |
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Leaves | persistent, light gray-green; blades narrowly cuneate, 0.5–3 × 0.2–0.5 cm, entire or 3(–5)-lobed (lobes 1.5–2 mm, less than 1/3 blade lengths, acute), faces silvery canescent. |
(pungently aromatic) deciduous or persistent, cauline (in lateral fascicles on vegetative shoots). |
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Involucres | globose, 2–3 × 1.5–2.5 mm. |
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Receptacles | epaleate, glabrous. |
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Florets | pistillate 0–2 (raylike, laminae to 1 mm); bisexual 1–3; corollas 1–1.5 mm (style branches of ray florets elongate, exsert, epapillate, tips acute; of disc florets, short, truncate, papillate). |
3–20, bisexual, fertile; corollas (pale yellow) funnelform. |
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Phyllaries | (8–15) ovate, canescent or tomentose. |
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Heads | (usually nodding) in arrays 6–25 × 1–4 cm (branches erect, somewhat curved). |
discoid (except A. bigelovii with, rarely, 1–2 raylike florets). |
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Cypselae | (ellipsoid, 5-ribbed) 0.8–1 mm, glabrous. |
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Pappi | 0. |
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2n | = 18, 36, 72. |
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Artemisia bigelovii |
Artemisia subg. Tridentatae |
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Phenology | Flowering early summer–late fall. | |||||||||||||||||||||||||||||||||||||||||
Habitat | Deserts, sandy or alkaline soils, rock outcrops | |||||||||||||||||||||||||||||||||||||||||
Elevation | 1000–2500 m (3300–8200 ft) | |||||||||||||||||||||||||||||||||||||||||
Distribution |
AZ; CA; CO; NM; NV; TX; UT
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North America; nw Mexico |
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Discussion | Artemisia bigelovii of the southwestern deserts is easily confused in the field with A. tridentata, even though it is well distinguished ecologically and morphologically. Systematic placement within subg. Tridentatae remains problematic. Presence of “ray” florets (though rare) and vestigial spines on the pollen (R. P. Wodehouse 1935) suggest a relationship with groups ancestral to Tridentatae. The species also has the unusual characteristic of lignified trichomes (L. M. Shultz 1986b). Further research may help to determine proper placement; its affinities may be with members of subg. Artemisia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Species 10 (10 in the flora). Difficulty in classification of Artemisia subg. Tridentatae has been complicated by transfer of North American species to Seriphidium (Y. R. Ling 1995b; W. A. Weber 1984b), a disposition not followed here. Species circumscription varies among authors, but most modern treatments recognize the species as defined here. The most useful field characteristics in sagebrush taxonomy are size of the plant, shape and lobing of the vegetative leaves, and size and shape of the flowering heads (A. A. Beetle 1960; A. H. Winward 1970). Differences in chromosome number are more useful in defining subspecies than species (E. D. McArthur et al. 1981; G. H. Ward 1953), and introgression among subspecies is common (McArthur et al. 1988; McArthur and S. C. Sanderson 1999). The following key relies on vegetative characteristics, and unless noted, descriptions of leaf size and lobing refer to the leaves found in the vegetative shoots proximal to arrays of heads. These ‘vegetative leaves’ occur in bundles, or fascicles that are part of the lateral shoots. They are subtended by an elongate leaf (termed ‘ephemeral’), which is attached to the primary stem and falls off early in the season. With the exception of Artemisia spiciformis, which retains its ephemeral leaves through most of the growing season, ephemeral leaves normally drop from the plant before the onset of flowering. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 19, p. 512. | FNA vol. 19, p. 509. | ||||||||||||||||||||||||||||||||||||||||
Parent taxa | Asteraceae > tribe Anthemideae > Artemisia > subg. Tridentatae | Asteraceae > tribe Anthemideae > Artemisia | ||||||||||||||||||||||||||||||||||||||||
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Synonyms | A. petrophila, Seriphidium bigelovii | A. unranked Tridentatae | ||||||||||||||||||||||||||||||||||||||||
Name authority | A. Gray: in War Department [U.S.], Pacif. Railr. Rep. 4(5): 110. (1857) | (Rydberg) McArthur: Amer. J. Bot. 68: 590. (1981) | ||||||||||||||||||||||||||||||||||||||||
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