Lowell E. Urbatsch, Loran C. Anderson, Roland P. Roberts, Kurt M. Neubig in Flora of North America (vol. 20)
Plants 10-250 cm. Stems erect or ascending to spreading, white to green, fastigiately branched, tomentose. Leaves (usually crowded) usually ascending to spreading; blades filiform to narrowly oblanceolate (mostly adaxially sulcate to concave), 10-70 × 0.3-10 mm, midnerves mostly evident, apices acute, faces glabrous or tomentose, often gland-dotted (lacking well-defined circular pits) ; axillary fascicles absent. Heads in rounded to flat-topped, cymiform arrays (to 12 cm wide). Peduncles 1-20 mm (bracts usually 0, sometimes 1-5, reduced, scalelike). Involucres obconic to subcylindric, 6-16 × 2-4 mm. Phyllaries 10-31 in 3-5 series (often in vertical ranks), tan, ovate to lanceolate, 1.5-14 × 0.7-1.5 mm, strongly unequal, mostly chartaceous (mostly keeled), midnerves raised for nearly entire lengths, expanded apically, apices acute to obtuse, abaxial faces resinous. Ray florets 0. Disc florets (4-)5(-6); corollas 6-12 mm. Cypselae tan, turbinate to cylindric or oblanceoloid, 3-8 mm, glabrous or hairy (often ± pilose or sericeous); pappi whitish, 3-13 mm. 2n = 18. Ericameria nauseosa is widespread, often abundant, and complex. This treatment is based largely on that by L. C. Anderson (1986b). Uncertainty about the specimen used by Pursh to establish E. nauseosa (as Chrysocoma nauseosa) is a possible source of confusion concerning the application of that name (which is in current use) and of the name Chrysothamnus speciosus Nuttall (J. L. Reveal et al. 1999). Anderson divided the species into two informal groups, the 'green forms' and the 'gray forms.' These two groups were formalized as subspp. nauseosa and consimilis by G. L. Nesom and G. I. Baird (1993), each containing varieties. Ericameria nauseosa is reported to hybridize with other species in the genus, and hybrid and formula names have been applied to them. Their synonymies were more fully summarized by Nesom and Baird.
Ericameria ×bolanderi (A. Gray) G. L. Nesom & G. I. Baird, based on Linosyris bolanderi A. Gray is the hybrid between E. discoidea and E. nauseosa (L. C. Anderson and J. L. Reveal 1966).
Ericameria ×uintahensis (L. C. Anderson) G. L. Nesom & G. I. Baird, 'Uinta rubber rabbitbrush,' based on Chrysothamnus nauseosus subsp. uintahensis L. C. Anderson, is the hybrid between E. nauseosa and E. parryi (L. C. Anderson 1984).
Ericameria ×viscosa (D. D. Keck) G. L. Nesom & G. I. Baird, based on Chrysothamnus nauseosus subsp. viscosus D. D. Keck, is the hybrid between E. cuneata and E. nauseosa (L. C. Anderson 1986b).
FNA 2006, Benson and Darrow 1981, Kearney and Peebles 1969
Common Name: rubber rabbitbrush Duration: Perennial Nativity: Native Lifeform: Shrub General: Broom-like shrubs up to 2 m tall; stems white to green, flexible, covered with dense, felt-like tomentum. Leaves: Alternate, sessile, usually crowded; blades linear to filiform, up to 7 cm long, midnerves mostly evident, surfaces glabrous to tomentose and often gland-dotted. Flowers: Flower heads yellow, discoid, and numerous in terminal clusters to 12 cm wide; involucre (ring of bracts wrapped around flower head) narrow, obconic to subcylindric, 6-14 mm high, the bracts (phyllaries) 10-30 in 3-5 series, in more-or-less vertical rows; disc florets generally 5 per head, the corollas yellow, 6-12 mm long. Fruits: Achenes tan, cylindric, 3-8 mm long, glabrous or hairy; topped with a whitish pappus, 3-13 mm long. Ecology: Found in open places in valleys, plains, and foothills from 2,000-8,000 ft (610-2440 m); flowers July-October. Distribution: Most of western N. Amer.; from Vancouver, CAN east to Saskatchewan and south to TX, NM, AZ and CA; south to c MEX. Notes: A highly variable species complex in size, form, pubescence and color; FNA recognizes 21 varieties. Distinguished by being a most-often gray-green, tomentose shrub with flexible stems in a broom-like growth form; filiform (threadlike) leaves; yellow flower heads arranged in flat-topped arrays, the flower heads narrow and elongated with very few (4-6) disc flowers and phyllaries with midnerves raised for the entire length. A larger plant than the similar Gutierrezia sarothrae (snakeweed); snakeweed also differs by having vibrant green herbage (rather than gray-green and tomentose in E. nauseosa); shorter leaves less than 1 cm long; smaller flower heads less than 1 cm long. The E. nauseosa complex is taxonomically poorly resolved and is even reported to hybridize with other Ericameria spp. In our region, it is clear that var. latisquamea exists and can be told apart by the densely tomentulose outer phyllaries and glabrous inner phyllaries. Of some question is the existence of var. nauseosa, which FNA indicates as not existing in our region (Plants DB says otherwise). Best course of action with this species is to make a good collection and record the height of the plant (shrub height appears several times in the key). Ethnobotany: Numerous uses as utilitarian items such as brooms, brushes, baskets, dye and arrows, and sometimes provides windbreaks. Bark makes green dye and flowers make yellow dye. Navajo used this plant for coughs, colds, fever, rheumatism, internal injuries, headache and menstrual pain. Etymology: Eric- is ancient root for heath or broom, and amari means bitter; nauseosa means to vomit or be nauseous. Synonyms: Chrysothamnus nauseosus Editor: SBuckley 2010, FSCoburn 2015, AHazelton 2016