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Published In: Species Plantarum 2: 845. 1753. (1 May 1753) (Sp. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 7/9/2009)
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Project Data     (Last Modified On 8/10/2009)

 

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3. Artemisia L. (wormwood, sage, mugwort)

Plants annual, biennial, or perennial herbs (shrubs elsewhere), sometimes from a woody rootstock, weakly to strongly aromatic, glabrous or sparsely to densely hairy. Stems erect or ascending, branched or unbranched, finely ridged. Leaves alternate and sometimes also basal, sessile or short-petiolate (the lowermost leaves usually long-petiolate in A. absynthium), sometimes with slightly broadened, more or less clasping bases. Leaf blades entire or variously lobed or compound, glandular and otherwise glabrous to variously hairy, the blade or lobes with 1 to several veins, these sometimes difficult to observe. Inflorescences terminal and often also axillary, spikes or racemes, sometimes grouped into terminal panicles, these usually elongate or pyramidal, the branches spicate, racemose, or sometimes reduced to small clusters sessile along the main axis, bractless or with bracts subtending the heads. Heads discoid, all of the florets perfect (the marginal florets sometimes only pistillate) and potentially producing fruits, or the marginal florets perfect and the central florets only staminate and not producing fruits. Involucre broadly ovoid to nearly cylindrical, the bracts more or less in 2–4 overlapping series, the outer ones somewhat shorter, narrowly ovate to linear, sharply pointed at the tip, variously glabrous or hairy and glandular, often with a green or brown midvein or subapical area, otherwise grayish tan to brown, usually flat, at least the innermost usually with the margins thin and papery. Receptacle usually strongly convex at flowering, not conspicuously elongating at fruiting, solid, naked or less commonly densely bristly-hairy. Disc florets numerous, the corolla yellow or greenish yellow, sometimes purplish-tinged, minutely glandular, the 5 lobes without resin canals, persistent, the tube not flattened toward the tip but sometimes slightly oblique at the tip, not becoming swollen at fruiting. Pappus absent. Fruits ellipsoid to ellipsoid-obovoid, less commonly nearly cylindrical, not or only slightly flattened, often somewhat asymmetric at the base, the tip often slightly obliquely truncate, relatively strongly 5–10-ribbed to inconspicuously nerved or lined, the surface otherwise usually glabrous, tan to brown. About 350 species, nearly worldwide.

The species of sagebrush in the western states are all shrubby members of the genus Artemisia. Various species have long been cultivated as ornamentals for their silvery foliage. The name wormwood comes from the use of some species in medieval times to treat intestinal worms. Various other species have been used as spices and flavorings. Because the genus is mainly wind-pollinated, some species, particularly A. annua, are considered bad hay fever plants.

 

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1 1. Leaves glabrous or sparsely hairy at maturity, never appearing woolly, felty, or silky on either surface, the green surfaces exposed

2 2. Leaves mostly unlobed or the larger ones sometimes with 1(2) pairs of slender lobes toward the base; plants perennial, with a hard rhizome or branched, woody rootstock, lacking a taproot at flowering ... 6. A. DRACUNCULUS

Artemisia dracunculus
3 2. Largest leaves 2 times pinnately compound or lobed, the remaining stem leaves sometimes only once compound or lobed, but then mostly with more than 2 pairs of leaflets or lobes, only the uppermost leaves unlobed or with 1 or 2 pairs of leaflets or lobes; plants annual or biennial, with a taproot at flowering

4 3. Ultimate leaflets and/or lobes mostly long and narrowly linear (threadlike), the margins entire; heads with the central florets staminate and not forming fruits, only the marginal florets perfect and developing fruits ... 4. A. CAMPESTRIS

Artemisia campestris subsp. caudata
5 3. Ultimate leaflets and/or lobes linear to narrowly elliptic-oblanceolate but not threadlike, the margins noticeably toothed (except on the sometimes threadlike and entire uppermost leaves); heads with all of the florets perfect and potentially developing fruits

6 4. Plants strongly aromatic when bruised; inflorescences appearing open-paniculate with the branches loosely flowered, the heads stalked; involucre 1.01.5(2.0) mm long ... 2. A. ANNUA

Artemisia annua
7 4. Plants odorless or nearly so when bruised; inflorescences appearing densely and narrowly paniculate or spikelike with short branches densely flowered, the heads sessile or nearly so; involucre 23 mm long ... 3. A. BIENNIS

Artemisia biennis
8 1. Leaves densely pubescent with woolly, felty, or silky hairs, at least on the undersurface, the grayish white pubescence hiding the surface

9 5. Leaves 0.51.5 cm long (including petiole) ... 7. A. FRIGIDA

Artemisia frigida
10 5. Largest leaves more than 1.5 cm long

11 6. Heads relatively large, the involucre 6.07.5 mm long; florets with the corolla 3.24.0 mm long ... 9. A. STELLERIANA

Artemisia stelleriana
12 6. Heads relatively small, the involucre 25 mm long; florets with the corolla 1.22.8 mm long

13 7. Receptacle with relatively long, bristly hairs between the florets ... 1. A. ABSINTHIUM

Artemisia absinthium
14 7. Receptacle naked

15 8. Leaves mostly less than 3(5) cm long (including the petiole), with the central axis (and lobes) 0.51.0(1.5) mm wide, often threadlike ... 5. A. CARRUTHII

Artemisia carruthii
16 8. Largest leaves more than 5 cm long (including the petiole), the central axis (and often also the lobes) more than 2 mm wide

17 9. Largest leaves entire or toothed to shallowly lobed or, if deeply lobed, then with the lobes either entire (not toothed) or with a pair of deep lobes, lacking stipulelike lobes at the base ... 8. A. LUDOVICIANA

Artemisia ludoviciana
18 9. Largest leaves with the primary lobes toothed or lobed, often with 1 or 2 pairs of small, stipulelike lobes at the leaf base ... 10. A. VULGARIS Artemisia vulgaris
 
 
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