Artemisia ludoviciana

Nuttall

Gen. N. Amer. Pl.2: 143. 1818

Common names: Silver wormwood white or silver sage
Synonyms: Artemisia vulgaris var. ludoviciana (Nuttall) Kuntze
Treatment appears in FNA Volume 19. Treatment on page 527. Mentioned on page 522, 524, 530, 532.
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Perennials, 20–80 (rarely to 120 in desert washes) cm, aromatic (rhizomatous). Stems relatively few to relatively numerous, erect, gray-green, simple or widely branched, hairy. Leaves cauline, uniformly gray-green, green, or white, or bicolor (white and green); blades linear to broadly elliptic, 1.5–11 × 0.5–4 cm, entire or lobed to relatively deeply pinnatifid, faces hairy. Heads (erect to nodding, peduncles 0 or 2–5 mm) in congested to open (widely branched) arrays. Involucres campanulate or turbinate, (1–)2–4(–5) × 2–5(–8) mm. Phyllaries (gray-green), lanceolate to ovate or obovate (margins narrowly hyaline), densely tomentose. Florets: pistillate 5–12; bisexual 6–45; corollas yellow, sometimes red-tinged, 1.5–2.8 mm, glabrous. Cypselae ellipsoid ca. 0.5 mm, (obscurely nerved) glabrous. 2n = 18, 36, 54.

Distribution

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North America, Mexico.

Discussion

Subspecies ca. 7 (6 in the flora).

References

None.

Key

1 Leaves usually relatively deeply lobed (1/3+ widths, nearly to midrib, proximal leaves sometimes entire); involucres 3–8 mm diam.; mountain meadows and slopes > 2
1 Leaves entire or relatively shallowly lobed (lobes to 1/3 widths); involucres 2–3(–4) mm diam.; desert valleys and mountains > 3
2 Involucres 4–5 × 4–8 mm Artemisia ludoviciana subsp. candicans
2 Involucres 3–4 × 3–5 mm Artemisia ludoviciana subsp. incompta
3 Heads in paniculiform arrays (4–)8–30 cm diam.; leaves mostly 1.5–2 cm Artemisia ludoviciana subsp. albula
3 Heads in paniculiform or racemiform arrays 1–6 cm diam.; leaves 1.5–11 cm > 4
4 Leaf margins plane Artemisia ludoviciana subsp. ludoviciana
4 Leaf margins revolute > 5
5 Leaves bicolor (gray-green and bright green), margins mostly entire, abaxial faces glabrous Artemisia ludoviciana subsp. redolens
5 Leaves gray-green, margins usually lobed, abaxial faces hairy Artemisia ludoviciana subsp. mexicana