Artemisia tridentata subsp. vaseyana

(Rydberg) Beetle

Rhodora 61: 83. 1959.

Common names: Mountain sagebrush
Endemic
Basionym: Artemisia vaseyana Rydberg in N. L. Britton et al., N. Amer. Fl. 34: 283. 1916
Synonyms: Artemisia tridentata var. pauciflora Winward & Goodrich Artemisia tridentata var. vaseyana (Rydberg) B. Boivin Seriphidium vaseyanum
Treatment appears in FNA Volume 19. Treatment on page 517. Mentioned on page 515, 516.

Shrubs, 60–80 (–150) cm (plants highly aromatic, crowns flat-topped). Vegetative branches of nearly equal lengths. Leaves (vegetative branches) broadly cuneate, 1.2–3.5 × 0.3–0.7 cm, regularly 3-lobed to irregularly toothed. Heads in paniculiform arrays 10–15 × 2–4 cm. Involucres 2–3 × 1.5–3 mm. Florets 3–9. Cypselae glabrous. 2n = 18, 36.


Phenology: Flowering mid summer–late fall.
Habitat: Montane meadows, usually in rocky soils, sometimes in forested areas
Elevation: 2000–2800 m

Distribution

V19-879-distribution-map.gif

B.C., Calif., Colo., Idaho, Mont., Nev., N.Dak., Oreg., S.Dak., Utah, Wash., Wyo.

Discussion

Subspecies vaseyana is the common sagebrush of mountain slopes and is the most abundant of all the subspecies of Artemisia tridentata. A. A. Beetle (1960) estimated that it dominates an area of approximately 260,000 square kilometers. That estimate remains reasonably accurate today even though sagebrush is often cleared (by burning, herbicide spray, or the practice of ‘chaining’) and replaced by grasses (especially crested wheatgrass) suitable for livestock grazing. The acreage in which sagebrush has been removed appears to be more than compensated by acreage where it has increased in abundance because of overgrazing. While there may be evidence of introgression with other subspecies of A. tridentata, the subsp. vaseyana is usually well-separated geographically and ecologically from the other three subspecies. Variation within subsp. vaseyana may warrant the recognition of two varieties. A few-flowered (6 or fewer florets) form occurs at lower elevations (usually less than 2300 m) than the more robust form (with more than 6 florets per head), occurring at higher elevations (generally more than 2300 m). The type specimen of A. vaseyana is the large-headed variant. Pending further study, I am including var. pauciflora Winward & McArthur as part of subsp. vaseyana. In areas where populations of subsp. vaseyana co-occur with subspecies of A. cana, introgression is common.

Selected References

None.

Lower Taxa

None.
not tailed +  and obtuse +
scarious +
spiciform +, racemiform +, paniculiform +  and corymbiform +
indeterminate +  and determinate +
Leila M. Shultz +
(Rydberg) Beetle +
decurrent +
Artemisia vaseyana +
compound +  and simple +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (3.5 cm35 mm <br />0.035 m <br />) +
3-lobed;cuneate +
0.1cm;0.7cm +
Mountain sagebrush +
zygomorphic +, actinomorphic +  and (3-)5-merous +
red +  and pale-yellow +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
winged +  and monomorphic +
fertile +  and bisexual +
fertile +  and bisexual +
B.C. +, Calif. +, Colo. +, Idaho +, Mont. +, Nev. +, N.Dak. +, Oreg. +, S.Dak. +, Utah +, Wash. +  and Wyo. +
2000–2800 m +
gland-dotted +
pistillate +, staminate +  and neuter +
fertile +  and bisexual +
winged +  and beaked +
dispersed +
Montane meadows, usually in rocky soils, sometimes in forested areas +
spiciform +  and racemiform +
in subcapitate clusters +  and singly +
indeterminate +
10 cm100 mm <br />0.1 m <br /> (15 cm150 mm <br />0.15 m <br />) +
heterogamous +  and homogamous +
2 cm20 mm <br />0.02 m <br /> (4 cm40 mm <br />0.04 m <br />) +
each +  and sessile +
0.1 cm1 mm <br />0.001 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
lanceolate +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
sessile +  and petiolate +
gray-green +
persistent +
1.2cm;3.5cm +
cauline +  and basal +
regularly 3-lobed;irregularly toothed +
0.3 cm3 mm <br />0.003 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
deltate +
entire +  and dentate +
2-carpellate +
persistent +
Flowering mid summer–late fall. +
2 +  and 20 +
styliferous +, neuter +  and pistillate +
sterile +  and fertile +
conic;convex;conic;convex;flat +
2 +  and 5 +
exalbuminous +
gray-brown +
1 +  and 10 +
not wand-like +
appendaged +  and truncate +
papillate +
Artemisia tridentata var. pauciflora +, Artemisia tridentata var. vaseyana +  and Seriphidium vaseyanum +
Artemisia tridentata subsp. vaseyana +
Artemisia tridentata +
subspecies +
funnel +  and subglobose +
cylindric +
perennial +, biennial +  and annual +