Artemisia arbuscula

Nuttall

Trans. Amer. Philos. Soc., n. s. 7: 398. 1841.

Common names: Low sagebrush
Endemic
Synonyms: Artemisia tridentata subsp. arbuscula (Nuttall) H. M. Hall & Clements Artemisia tridentata var. arbuscula (Nuttall) McMinn Seriphidium arbusculum
Treatment appears in FNA Volume 19. Treatment on page 511. Mentioned on page 512, 514, 515.

Shrubs, 10–30 (–50) cm, aromatic; root-sprouting. Stems gray-green to brown, glabrate (diffusely branched from bases, brittle). Leaves (vegetative stems) persistent, gray-green; blades broadly to narrowly cuneate, 3–10 × 2–5 mm, lobed (lobes 3, oblong-linear, to 1/3 blade lengths, mostly 1–3 mm wide, flat, obtuse, laterals sometimes 2–3-fid; leaves on flowering-stems deciduous, blades narrowly cuneate, deeply 3-lobed), faces densely hairy (not sticky resinous). Heads usually borne singly, rarely (1–4, erect, mostly sessile, in pedunculate clusters) in spiciform or paniculiform arrays 2–9 × 0.5–2 cm (branches slender). Involucres campanulate or globose-ovoid, (1.5–) 2–4 (–5) × 1.5–4.5 mm. Phyllaries (margins green) ovate (outer) to oblong, pubescent or tomentose. Florets 4–6 (–10); corollas 1.5–2 mm, glabrous. Cypselae (light-brown) 0.7–0.8 mm, resinous.

Distribution

V19-862-distribution-map.gif

Calif., Colo., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.

Discussion

Subspecies 3 (3 in the flora).

Artemisia arbuscula is one of the more perplexing species in the Tridentatae complex. Anatomic and morphologic characteristics suggest multiple hybrid origins for the subspecies. Deciduous leaves of flowering stems in plants that otherwise have persistent leaves suggest a hybrid origin involving plants of the A. tridentata and A. cana lineages. In most instances, populations of A. arbuscula appear to be reproductively stable. The disposition of Artemisia arbuscula subsp. longicaulis Winward & McArthur (with 2n = 54) has not been determined.

Selected References

None.

Key

1 Involucres 2–4.5 mm diam.; usually in rocky soils; flowering mid–late summer Artemisia arbuscula subsp. arbuscula
1 Involucres 1.5–2.5 mm diam.; clays or stony soils; flowering early spring–late summer > 2
2 Leaves broadly cuneate (4–10 × 2–5 mm, often irregularly lobed, lobes rounded, middle lobes overlapping lateral lobes); usually in clay soils; flower- ing early spring Artemisia arbuscula subsp. longiloba
2 Leaves narrowly cuneate (5–10 × 3–6 mm, lobed, lobes 1/2+ blade lengths, laterals to 1 mm wide, of-ten acute); usually in stony soils; flowering mid–late summer Artemisia arbuscula subsp. thermopola
... more about "Artemisia arbuscula"
not tailed +  and obtuse +
scarious +
paniculiform +  and spiciform +
indeterminate +  and determinate +
2 cm20 mm <br />0.02 m <br /> (9 cm90 mm <br />0.09 m <br />) +
0.5cm +  and 2cm +
Leila M. Shultz +
Nuttall +
decurrent +
Tridentatae +
compound +  and simple +
0.3 cm3 mm <br />0.003 m <br /> (1 cm10 mm <br />0.01 m <br />) +
lobed;cuneate +
2mm;5mm +
Low sagebrush +
zygomorphic +, actinomorphic +  and (3-)5-merous +
red +  and pale-yellow +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
winged +  and monomorphic +
fertile +  and bisexual +
fertile +  and bisexual +
Calif. +, Colo. +, Idaho +, Mont. +, Nev. +, Oreg. +, Utah +, Wash. +  and Wyo. +
gland-dotted +
pistillate +, staminate +  and neuter +
fertile +  and bisexual +
winged +  and beaked +
dispersed +
spiciform +  and racemiform +
indeterminate +
heterogamous +  and homogamous +
each +  and sessile +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 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 /> (0.4 cm4 mm <br />0.004 m <br />) +
globose-ovoid;campanulate +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.45 cm4.5 mm <br />0.0045 m <br />) +
sessile +  and petiolate +
gray-green +
persistent +
cauline +  and basal +
deltate +
entire +  and dentate +
2-carpellate +
persistent +
tomentose +  and pubescent +
2 +  and 20 +
Trans. Amer. Philos. Soc., n. s. +
styliferous +, neuter +  and pistillate +
sterile +  and fertile +
conic;convex;conic;convex;flat +
2 +  and 5 +
exalbuminous +
gray-green +  and brown +
1 +  and 10 +
not wand-like +
appendaged +  and truncate +
papillate +
Artemisia tridentata subsp. arbuscula +, Artemisia tridentata var. arbuscula +  and Seriphidium arbusculum +
Artemisia arbuscula +
Artemisia subg. Tridentatae +
species +
funnel +  and subglobose +
cylindric +
perennial +, biennial +  and annual +
shrub +  and root-sprouting +