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Montana Field Guide

Montana Field Guides

Gray Horsebrush - Tetradymia canescens

Native Species

Global Rank: G5
State Rank: S4

Agency Status
USFWS:
USFS:
BLM:
MNPS Threat Rank:
C-value: 4

External Links






 
General Description
Plants to 80 cm tall. Stems unarmed; twigs tomentose. Primary leaves narrowly oblanceolate, 1–2 cm long, tomentose; fascicled leaves smaller. Inflorescence heads terminating branches in a corymbiform array. Involucre 7–10 mm high; phyllaries 4, tomentose. Disk corollas 7–12 mm long. Achenes 3–5 mm long glabrous or sericeous (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Diagnostic Characteristics
Montana has 2 Tetradymia species:

Gray Horsebrush - Tetradymia canescens
*Stems: Unarmed.
*Flower Heads: Grow in clusters (corymbiform) at tips of stems.

Short-spine Horsebrush - Tetradymia spinosa, SOC
*Stems: Spiny.
*Flower Heads: Grow from leaf axils.

Possible look-alikes include yellow-flowered shrubs in the Sunflower (Asteraceae) Family:

Tetradymia - Horsebrush
*Flower Heads: Ray florets are absent and pappus is of capillary bristles.
*Twigs: White-tomentose (hairy) with or without spines andUpper Leaves are fascicled.

Artemisia - Sagebrush
*Flower Heads: Arranged in a raceme or panicle, involucral bracts in 4-7 unequal rows, and pappus is absent.
*Leaves: Usually lobed, but some species with simple leaves.

Ericameria - Goldenbrush / Rabbitbrush
*Flower Heads: a) Ray florets are absent and pappus is of capillary bristles, or b) Some ray florets are present.
*Twigs: a) White-tomentose (hairy) without spines and upper Llaves are mostly not fascicled, or b) glabrous and greenish.

Chrysothamnus - Rabbitbrush
*Flower Heads: Ray florets are absent and pappus is of capillary bristles.
*Twigs: Glabrate to puberulent and leaves are resin-dotted.

Gutierrezia sarothrae - Broom Snakeweed
*Flower Heads: Arranged in flat-topped clusters (corymbiform), ray florets present, and pappus is of jagged (erose) scales.
*Plants are short, often less than 30 cm tall.

Lorandersonia linifolia - Spearleaf Rabbitbrush, PSOC
*Flower Heads: Ray florets are absent and pappus is of capillary bristles.
*Twigs: Mostly without hairs (glabrous), has a whitish epidermis, and leaves lack glands.

Species Range
Present
 


Range Comments
BC south to CA, AZ and NM (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 383

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Habitat

References
  • Additional ReferencesLegend:   View Online Publication
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    • Grove, A.J. 1998. Effects of Douglas fir establishment in southwestern Montana mountain big sagebrush communities. M. Sc.Thesis. Bozeman, MT: Montana State University. 150 p.
    • Guenther, G.E. 1989. Ecological relationships of bitterbrush communities on the Mount Haggin Wildlife Management Area. M.Sc. Thesis. Bozeman, MT: Montana State University. 73 p.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Matlock-Cooley, S.J. 1993. Interaction between Deermice, Antelope Bitterbrush, and cattle in southwest Montana. M.Sc. Thesis. Bozeman, MT: Montana State University 84 p.
    • Quire, R.L. 2013. The sagebrush steppe of Montana and southeastern Idaho shows evidence of high native plant diversity, stability, and resistance to the detrimental effects of nonnative plant species. M.Sc. Thesis. Bozeman, MT: Montana State University. 124 p.
    • Seipel, T.F. 2006. Plant species diversity in the sagebrush steppe of Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 87 p.
    • South, P.R. 1957. Food habits and range use of the mule deer in the Scudder Creek area, Beaverhead County, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 34 p.
    • Stevens, D.R. 1965. Range relationships of elk and livestock in the Crow Creek drainage, Elkhorn Mountains, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 68 p.
    • Taylor, K., T. Brummer, L.J. Rew, B.D. Maxwell. 2014. Bromus tectorum response to fire varies with climate conditions. Ecosystems 17(6): 960-973. http://dx.doi.org/10.1007/s10021-014-9771-7
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Citation for data on this website:
Gray Horsebrush — Tetradymia canescens.  Montana Field Guide.  .  Retrieved on , from