Atriplex

Linnaeus

Sp. Pl. 2: 1052. 1753

,

Gen. Pl. ed. 5, 472. 1754

Common names: Orach saltbush
Etymology: ancient Latin name
Treatment appears in FNA Volume 4. Mentioned on page 226, 260, 268, 293.
Herbs or shrubs, annual or perennial, monoecious or dioecious, often with bladderlike hairs that collapse to form silvery or scurfy (mealy) vesture, less often with elongate trichomes. Leaves persistent or tardily deciduous, alternate, partially opposite, or opposite, sessile or petiolate; blade entire, serrate, or lobed, with venation either of Kranz-type or normal dicotyledonous type, axillary buds inconspicuous or lacking. Inflorescences axillary or terminal; flowers borne in axillary clusters or glomerules, or in terminal spikes or spicate panicles. Staminate flowers with 3–5-parted calyx, ebracteate; stamens 3–5. Pistillate flowers lacking perianth, pistil naked, or in few species with (1–)3–5-lobed perianth, commonly enclosed within pair of foliaceous bracteoles; stigmas 2. Fruiting bracteoles enlarged in fruit, of various shapes and variously connate or not, thickened, and appendaged; pericarp free, tightly enclosed in the fruiting bracteoles. Seeds flattened, mainly vertical; radicle inferior, lateral, or superior. x = 9.

Discussion

Species ca. 250 (62 in the flora).

Many species of Atriplex are halophytic, others occupy soils low in dissolved particulates.

Prior to the 1900s, the genus Suckleya was treated within Atriplex, but its obcompressed fruiting bracteoles are quite unlike anything in Atriplex, and the plants were recognized as a distinct genus.

Excluded species:

Atriplex barclayana subsp. dilatata H. M. Hall & Clements, Publ. Carnegie Inst. Wash. 326: 315. 1923

A new species, most related to Atriplex argentea and A. expansa, judging from the habit; but the fruits are flat and their sides not appendaged or muricate.” The plant was described from San Benito Island, Baja California.

Atriplex nitens Schkuhr, Bot. Handb. 3: 541. 1803

P. C. Standley (1916) reported this species in New York, New Jersey, South Dakota, and Oregon.

P. Aellen (1964) wrote: “Like 4 [i.e., A. hortensis] but the leaves white beneath; bracteoles oblong-cordate, conspicuously reticulate-veined.” Specimens having at least some of the above noted characteristics occur here and there among the North American materials of A. hortensis, and the name nitens is here in considered in synonymy of that species. It belongs to sect. Atriplex.

Atriplex nodosa Greene, Pittonia 1: 40. 1887

This name was apparently not taken up, even in synonymy, by either L. Abrams and R. S. Ferris (1923–1960, vol. 2) or P. A. Munz (1959), but was cited as a synonym of Atriplex argentea by P. C. Standley (1916). H. M. Hall and F. E. Clements (1923) cited this as a synonym of “A. argentea expansa,” based on “An insect stung monstrosity, according to Jepson (Fl. Calif. 436, 1914).”

Atriplex sibirica Linnaeus, Sp. Pl. ed. 2, 2: 1493. 1763

This was supposedly collected in northeastern United States, but no specimens have been seen from the flora area. It belongs to sect. Obione.

Atriplex vesicaria Heward ex Bentham, Fl. Austral. 5: 172. 1870

The section Dialysex, to which Atriplex vesicaria belongs, is treated in the Australian flora with sixteen species; A. vesicaria with eight subspecies; its records in the United States, if any, are not known to me. It would not, in any case, be treated with the herbaceous species. H. M. Hall and F. E. Clements (1923) noted that this species, and the related A. holocarpa, have both been grown in American gardens with the thought of using both of them as forage plants, but neither of them found suitable for general planting.

Keys

Key Index

1 Plants perennial shrubs [20c. Atriplex subg. Pterochiton, in part] Key 4
1 Plants annual or perennial herbs > 2
2 Leaves usually green on both surfaces, glabrous or sparingly powdery or finely scurfy Key 1
2 Leaves white to gray, densely and finely scurfy, especially adaxially > 3
3 Plants perennial Key 2
3 Plants annual Key 3

Key 1

1 Pistillate flowers of 2 kinds: some with calyx 3-5-lobed and seed horizontal, others lacking perianth, enclosed in pair of bracteoles, seed vertical; fruiting bracteoles samaralike, strongly compressed, oval to orbicular or ovate; plants widespread in North America [20a.1. Atriplex sect. Atriplex] Atriplex hortensis
1 Pistillate flowers all alike or, if dimorphic, both kinds lacking perianth, enclosed within bracteoles, and seed vertical; fruiting bracteoles variously compressed (orbicular in A. heterosperma) > 2
2 Bracteoles ± thickened with spongy tissue, especially toward base [20a.2. Atriplex sect. Teutliopsis] > 3
2 Bracteoles not thickened (except A. joaquiniana) > 7
3 Lower leaves linear or ovate-lanceolate, sometimes toothed and/or with proximalmost lobe largest, but then not triangular, or if so leaves thick textured > 4
3 Lower leaves (sometimes all or most) triangular and thin textured > 5
4 Leaves linear to lanceolate or oblong, thin, green or slightly scurfy when young; seeds ovoid, not wider than long; coastal e Canada and ne United States, w disjunctly to Pennsylvania, Ohio, and Indiana Atriplex littoralis
4 Leaves ovate-lanceolate or linear, or triangular or triangular-hastate, typically thickened and ± scurfy, even in age; seeds ellipsoid, wider than long; broad distribution from coastal e Canada and United States, and c and w United States Atriplex dioica
5 Bracteoles, some or all, short stipitate, margin irregularly denticulate to laciniate, lateral angles of faces usually developed into 1-3 teeth; Cape Breton coast, Newfoundland, Nova Scotia, and New Brunswick Atriplex glabriuscula
5 Bracteoles all sessile, margin entire or slightly toothed, lateral angles shortly pointed but not definitely toothed; geography below > 6
6 Inflorescence with leafy bracts to the tip, glomerules loose, irregularly spaced; bracteoles thick spongy, margin united to middle; seeds 2.5+ mm wide, usually not distinctly dimorphic, dark brown to black, irregularly biconvex; radicle median, ± antrorse; coastal e United States, from New Jersey n to Maine and Nova Scotia and n to Newfoundland and Labrador, and w disjunctly to Hudson Bay and n Alberta Atriplex glabriuscula
6 Inflorescence with leafy bracts only at base, glomerules tight, contiguous or irregularly spaced; bracteoles thin to slightly thickened and spongy, margin united only at base; seeds mostly less than 2.5 mm wide, usually distinctly dimorphic, mostly small and glossy black, but also some larger, and dull brown, flattened and disc-shaped; radicle subbasal, obliquely antrorse to spreading; plant a weedy introduction of broad distribution in United States and s Canada Atriplex prostrata
7 Plants mostly less than 1.2 dm; proximal leaves lanceolate to rhombic-ovate, bases cuneate to attenuate; bracteoles rhombic-ovate, thin herbaceous or membranaceous, entire, free to base; seeds black, lustrous, biconvex, 1.2-2.5 mm wide, with subbasal, spreading radicle; plants in the sublittoral zone on coasts of Newfoundland Atriplex nudicaulis
7 Plants mostly more than 1.2 dm; proximal leaves, bracteoles, and seeds not simultaneously as above; distribution various > 8
8 Fruiting bracteoles ovate to elliptic or orbiculate-cordate > 9
8 Fruiting bracteoles never orbiculate-cordate, frequently toothed, usually with lateral angles > 11
9 Bracteoles ovate to widely triangular, surfaces often 2-tuberculate, margin toothed; leaves usually thickened, ± scurfy, even at maturity Atriplex dioica
9 Bracteoles orbiculate-ovate, surfaces smooth, margin entire; leaves usually thin, green on both sides, not or scarcely scurfy > 10
10 Leaves broadly triangular-hastate; widely distributed from Quebec, w to Brit- ish Columbia and s to California, Nevada, Utah, and Colorado Atriplex heterosperma
10 Leaves mostly lanceolate to narrowly hastate; s British Columbia, adjacent Alberta, and South Dakota Atriplex oblongifolia
11 Bracteoles (2-)2.5-3(-4.5) mm; leaf blades deltoid to rhombic-ovate or oblong-ovate, coarsely toothed; saline soils in Sacramento Valley and east San Francisco Bay vicinity and San Joaquin Valley, California Atriplex joaquiniana
11 Bracteoles mainly 4-10+ mm; leaf blades hastate or entire, lanceolate to oblong; coastal salt marshes or ruderal weedy species of broad distribution > 12
12 Largest bracteoles strap-shaped or ovate-lanceolate; halophytes of w and nw coastal areas of North America Atriplex gmelinii
12 Largest bracteoles ovate, ovate-triangular, or rhombic; e coastal North America (disjunctly westward) or widespread ruderal weeds > 13
13 Radicle of brown seeds basal and spreading; e coastal salt marshes and disjunctly w to Hudson Bay and n Alberta Atriplex glabriuscula
13 Radicle of brown seeds subbasal to median and antrorse; widespread ruderal weeds > 14
14 Bracteoles rhombic, margin united almost to middle, lateral angles definite; terminal inflorescence with densely compressed, ± uniform- sized bracteoles; distal leaves green on both sides Atriplex patula
14 Bracteoles ovate or triangular-ovate, margin free to base, lateral angles lacking; terminal inflorescence with loosely spaced, larger and smaller bracteoles; distal leaves whitish abaxially Atriplex oblongifolia

Key 2

1 Plants dioecious; leaves sessile, mostly opposite [20b.3i. Atriplex subg. Obione subsect. Californicae, for the most part] > 2
1 Plants monoecious; leaves various, but if sessile and mostly opposite, of different distribution > 3
2 Leaves 2-5 mm, subequal to internodes; fruiting bracteoles 2-3 mm; coastal or near coastal s Texas and adjacent Mexico Atriplex matamorensis
2 Leaves 8-25 mm, often surpassing internodes; fruiting bracteoles 4-8 mm; coastal Santa Barbara County, California, Baja California, Mexico Atriplex watsonii
3 Leaves sessile, blade 5-20 × 1.5-5 mm; fruiting bracteoles 3 mm, rhombic-ovate, acute, sessile, scarcely united, entire; coastal and insular Marin County, California s to Baja California, Mexico [20b.3i. Atriplex subg. Obione subsect. Californicae, in part] Atriplex californica
3 Leaves subsessile to long petiolate, blade and fruiting bracteoles mostly more than 3 mm, but if shorter, not from coastal California > 4
4 Fruiting bracteoles (5-)6-12 mm, fibrous and spongy or merely spongy-thickened > 5
4 Fruiting bracteoles mainly 3-6 mm, not fibrous or spongy thickened > 7
5 Fruiting bracteoles obovoid-globular, summit closed by 2 erect, appressed, entire or 3-toothed valves; plants known from cultivation in Wyoming and Texas [20a.4. Atriplex sect. Spongiocarpus, in part] Atriplex holocarpa
5 Fruiting bracteoles variously shaped, bearing 1 or 2 appendages; different distributions > 6
6 Fruiting bracteoles 5-7 mm, broadly ovate in profile, entire or dentate, usually with wartlike projections on faces; sea beaches and coastal strand, occasionally inland, from Humboldt County, California, south to Baja Cali- fornia, Mexico [20b.3h. Atriplex sect. Obione subsect. Leucophyllae] Atriplex leucophylla
6 Fruiting bracteoles 6-12 mm, broadly turbinate or hemispheric, flattened at summit, bordered by a narrow horizontal wing or acutely angled; plants escaped from cultivation in San Joaquin Valley and San Diego County, California [20a.4. Atriplex sect. Spongiocarpus, in part] Atriplex lindleyi
7 Seeds dimorphic: black, 1.5-1.7 mm, or brown, 2 mm; bracteoles fleshy; plants low growing, many stemmed; leaf margin irregularly dentate; introduced, sw British Columbia and Washington, to s California, s Arizona, s Nevada, sw Utah, s Arizona, s New Mexico, and Texas [20a.5. Atriplex sect. Semibaccata, in part] Atriplex semibaccata
7 Seeds monomorphic, either black or brown; bracts not fleshy; plants not low growing; leaf margin entire to dentate; various or other distribution > 8
8 Petioles to 1/2 as long as blades, or some blades typically more than 2.5 cm > 9
8 Petioles short (much less than 1/2 as long as blades) or lacking, blades of various lengths > 10
9 Fruiting bracteoles 3 mm and as wide at apex, bluntly deltoid to circular, swollen, hard, smooth, denticulate at apex, faces unappendaged; Australian species [20a.5. Atriplex sect. Semibaccata, in part, Atriplex muelleri Bentham, see 17 Atriplex semibaccata] Atriplex semibaccata
9 Fruiting bracteoles (3-)5-7 mm, 2-4 mm broad, cuneate-orbicular, margin sharply dentate, faces with appendages or unappendaged; indigenous plants from nc to s California, w and s Nevada, Arizona, New Mexico, w and n Texas, w Oklahoma Atriplex argentea
10 Leaves sinuate-dentate; fruiting bracteoles rhombic, widest and 2- to 4-toothed beyond middle; plants known from s California, e to s Utah [20a.5. Atriplex sect. Semibaccata, in part] Atriplex suberecta
10 Leaves variously toothed or entire; fruiting bracteoles variously shaped and toothed; various or other distribution > 11
11 Fruiting bracteoles 2-4 mm wide, orbicular, subsessile to short stipitate, strongly compressed, united except at thin margin, margin dentate, terminal teeth often prominent, faces smooth; Mojave and Colorado deserts, California and adjacent s Arizona Atriplex elegans
11 Fruiting bracteoles, at least some, more than 4 mm, rhombic or obovate to cuneate-orbiculate, orbiculate, or obovate, margin deeply and acutely dentate, faces variously toothed or appendaged, the terminal teeth not conspicuous; various or other distribution > 12
12 Faces of cuneate-orbiculate fruiting bracteoles with 2 dentate crests or covered with irregular, conic-acute, corky tubercles; sandy seashores, s Carolina to s Florida and w to coastal w Texas Atriplex pentandra
12 Faces of obovate or orbiculate fruiting bracteoles without dentate crests or corky tubercles, usually smooth; saline or alkaline substrates in California, Nevada, Arizona, and Utah > 13
13 Fruiting bracteoles 2-3 mm, obovate, united 1/2 of length, free margin deeply and sharply dentate, faces smooth or sometimes tuberculate; Santa Barbara and Los Angeles to w San Bernardino Counties, California Atriplex coulteri
13 Fruiting bracteoles often larger, suborbiculate, or orbiculate, united except at thin margin, margin dentate, terminal teeth often prominent, faces often smooth; interior California, Nevada, Arizona, and Utah > 14
14 Staminate flowers in terminal spikes, pistillate ones in axillary clusters; Sacramento and San Joaquin valleys, California Atriplex fruticulosa
14 Staminate flowers in axillary clusters, or staminate and pistillate mixed, usually in axillary clusters; e of Sierra Nevada, in s California, e to Rio Grande Valley of s Texas, and s to Mexico Atriplex elegans

Key 3

1 Leaf blades all or most of them dentate or sinuate-dentate, leaves all alternate, or opposite only at proximalmost 1-3 nodes > 2
1 Leaf blades not all dentate, some, or all, of them entire, leaves commonly opposite or subopposite at proximalmost nodes > 6
2 Fruiting bracteoles widest at middle, entire below middle, 2-4-toothed beyond middle; s California [20a.5. Atriplex sect. Semibaccata, in part] Atriplex suberecta
2 Fruiting bracteoles mostly widest below middle, variously toothed, tuberculate, or entire; various or other distribution > 3
3 Leaf blades orbiculate or suborbiculate, flabellate to broadly obtuse at base; fruit flask-shaped in outline; Milk River Valley, Upper Missouri, south to Colorado [an Atriplex look-alike, Suckleya suckleyana (Torrey ex A. Gray) Rydberg] > 3
3 Leaves mainly ovate to lanceolate, acute to obtuse basally; various distribution [20a.3. Atriplex sect. Sclerocalymma] > 4
4 Plants erect; leaves with Kranz anatomy; seeds 2-2.5 mm wide; common, widespread weedy species mainly in saline substrates, widely distributed in United States and less so in s Canada Atriplex rosea
4 Plants decumbent; leaves with or without Kranz anatomy; seeds 3.5-4 mm wide (1.5-2 mm in A. tatarica); rare coastal halophytes of sandy beaches bordering Gulf of St. Lawrence, Canada, and along Atlantic coast to Alabama > 5
5 Seeds 1.5-2 mm; leaves without Kranz anatomy; staminate glomerules arranged in terminal panicles or spikes to several cm; plants robust, stems usually 2-15 dm, leaves often more than 5 cm; rare ballast waifs, introduced from Europe, from Massachusetts to Pennsylvania, and disjunctly in coastal Alabama Atriplex tatarica
5 Seeds 3.5-4 mm; leaves with Kranz anatomy; staminate glomerules in distal axils and in short dense terminal spikes to 1 cm; plants small, stems less than 3 dm; Gulf of St. Lawrence, Canada Atriplex laciniata
6 Perianth of staminate flowers cup-shaped, lobes fleshy-crested on back, pink; bracteole margin united to apex; high plains and steppes, se Alberta and s Saskatchewan, e Montana, w North Dakota, South Dakota, Wyoming, and nw Colorado [20b.2. Atriplex subg. Obione sect. Endolepis] Atriplex suckleyi
6 Perianth of staminate flowers not cup-shaped, lobes ovate, rounded on back, green in center, becoming membranous near margins; bracteole margin united at base or to middle; various or other distribution > 7
7 Fruiting bracteoles 3-7 mm wide, enclosing 2-5 flowers, these with perianth of 5 hyaline scales 1-1.2 mm; leaves without Kranz anatomy; mainly on Mancos Shale and Morrison formations, Four Corners vicinity, Colorado, Utah, New Mexico [20b.1. Atriplex subg. Obione sect. Pleianthae] Atriplex pleiantha
7 Fruiting bracteoles of various sizes, not enclosing more than 1 flower; leaves mainly with Kranz anatomy (except A. covillei); of various or other distribution > 8
8 Bracteoles on stipes 2-6 mm, body 5-6 mm thick, globose, with hornlike ap- pendages on both faces; se Utah Atriplex saccaria
8 Bracteoles variously sessile or, if stipitate, not otherwise as above > 9
9 Bracteoles samaralike, orbicular, often over 10 mm, margin 2-4 times as wide as body; staminate flowers in deciduous terminal panicles; local in e Utah, and wc Colorado Atriplex graciliflora
9 Bracteoles commonly less than 10 mm (mostly much less; 5-20 mm in A. phyllostegia), margin usually little if at all wider than body; staminate flowers in panicles or some or all in axillary glomerules; various or other distribution > 10
10 Fruiting bracteoles orbicular, finely and regularly radiately dentate to base, strongly compressed; deserts in se California and e to sw Utah, s Nevada, s Arizona, s New Mexico, w Texas, and in Sonora and Chihuahua [20b.3g. Atriplex subg. Obione subsect. Arenariae, in part] Atriplex elegans
10 Fruiting bracteoles not orbicular, or if so, never radiately dentate to base and not at once strongly compressed; other distribution > 11
11 Leaf blades oval to ovate or ovate-lanceolate, hastate or not; w Nevada and Great Valley of California > 12
11 Leaf blades variously shaped, if as above, mainly of other distribution > 13
12 Leaves oval to ovate, seldom if ever with long-attenuate, hastate lobes; plants with Kranz anatomy; w Nevada [20b.4. Atriplex subg. Obione sect. Phyllostegiae] Atriplex phyllostegia
12 Leaves ovate-lanceolate, mainly with acute to long-attenuate hastate lobes; plants without Kranz anatomy; w Nevada and c and s California [20b.5. Atriplex subg. Obione sect. Covilleiae] Atriplex covillei
13 Bracteoles 4-7 mm wide, variably and irregularly 3-7-cleft, typically constricted near middle and with terminal lobes 1.5-2.8 mm, doubly cristate on faces or smooth; Kleberg, LaSalle, Starr, and Webb counties, s coastal Texas [20b.3c. Atriplex subg. Obione subsect. Argenteae, in part] Atriplex klebergorum
13 Bracteoles less than 4-6 mm wide, or if that wide, then differing otherwise or of other distribution > 14
14 Bracteoles deltoid to ovate or hastate-ovate to ovate-oblong, broadest at or near base, often about twice as long as broad, small, sparingly dentate or tuberculate, or entire or smooth, acute; leaves small, sessile, blade typically entire, ovate to linear > 15
14 Bracteoles broadest near or above middle, usually rounded or truncate at apex, or if not so, leaves dentate; leaves usually large and often some petiolate (but see also A. coronata) > 24
15 Leaves and/or branches opposite, at least proximalmost [20b.3f. Atriplex subg. Obione subsect. Pusillae, in part] > 16
15 Leaves and branches all alternate > 18
16 Plants tending to sprawl, with leaves and foliose bracts tending to recurve Atriplex parishii
16 Plants erect or ascending, with leaves and foliose bracts straight or nearly so > 17
17 Proximal leaves with rounded base, with both leaves and foliose bracts somewhat thickened and stiffly ascending; fruiting bracteoles 2.5-3.5 mm, ovate to rhombic; Kern Lake, s San Joaquin Valley, California Atriplex tularensis
17 Proximal leaves acute to obtuse at base, with both leaves and foliose bracteoles rather thin and merely ascending; fruiting bracteoles 2.5-4 mm, broadly deltate to suborbiculate in profile; San Joaquin Valley, Kern and Fresno counties, California Atriplex coronata
18 Fruiting bracteoles 1.5-2 × 1-1.5 mm, ovate-oblong, fused to near summit, tridentate apically, occasionally with marginal or less commonly with facial appendages; se Utah [20b.3c. Atriplex subg. Obione subsect. Argenteae, in part] Atriplex powellii
18 Fruiting bracteoles not at once as above; various or other distribution [20b.3f. Atriplex subg. Obione subsect. Pusillae, for the most part] > 19
19 Leaf blades of at least some proximalmost leaves cordate at base; nc and c California Atriplex cordulata
19 Leaf blades rounded to acute or at most subcordate at base; various distribution > 20
20 Branches copiously villous, at least around inflorescence Atriplex parishii
20 Branches merely scurfy > 21
21 Faces of bracteoles tuberculate > 22
21 Faces of bracteoles smooth > 23
22 Leaf blades mainly 0.4-2.5 × 0.1-0.3 cm, linear to narrowly lanceolate; fruiting bracteoles ovate to cuneate; Utah, Wyoming, and Colorado [20b.3e. Atriplex subg. Obione subsect. Wolfianae] Atriplex wolfii
22 Leaf blades 0.2-0.4 × 0.1-0.3 cm, ovate to ovate-lanceolate; fruiting bracteoles ovate-oblong; Glenn, Merced, and Tulare counties, California Atriplex parishii
23 Bracteoles 2-3 mm, subhastate, denticulate, or crenulate; stems mainly not suffused with red; c valley of California southward Atriplex parishii
23 Bracteoles 1-2 mm, ovate, entire; stems suffused with red; ne California, se Oregon, Nevada Atriplex pusilla
24 Leaf blades, most of them, deltoid to deltoid-ovate or broadly ovate, broadest at or near base (lanceolate to elliptic in A. coronata), usually entire > 25
24 Leaf blades neither deltoid nor ovate, usually broadest at or beyond middle, in few species leaves broadest at base and conspicuously dentate > 31
25 Leaf blades often cordate at base; fruiting bracteoles of 2 kinds on each plant; s Wyoming, e Utah, n Arizona, nw New Mexico, and w Texas [20b.3b. Atriplex subg. Obione subsect. Saccariae] Atriplex saccaria
25 Leaf blades never cordate at base or, in some, sessile distal ones sometimes cordate-clasping; fruiting bracteoles all similar on same plant > 26
26 Bracteoles panduriform (fiddle-shaped) in outline (with 2 lateral rounded lobes lateral to terminal tooth), faces often obscured by cristate or unaligned appendages; leaf blades conspicuously 3-veined; Alberta, Saskatchewan, se Oregon, sw Idaho, Oregon, Utah, nw New Mexico, Colorado, Wyoming, South Dakota, Montana [20b.3c. Atriplex subg. Obione subsect. Argenteae, in part] Atriplex powellii
26 Bracteoles not panduriform; leaf blades not conspicuously 3-veined > 27
27 Bracteoles broadly rhombic, toothed beyond middle; Sacramento and San Joaquin valleys, California [20.b.3f. Atriplex subg. Obione subsect. Pusillae, in part] Atriplex cordulata
27 Bracteoles of various shapes and teeth various; various or other distribution > 28
28 Bracteoles dentate only at truncate apex, small; s British Columbia, Alberta, and sw Saskatchewan, s to California, Nevada, Utah, Colo- rado [20b.3d. Atriplex subg. Obione subsect. Truncatae] Atriplex truncata
28 Bracteoles dentate well below apex, often to base, large; other distribution > 29
29 Leaf blades closely repand-dentate; nc to s California, w and s Nevada, Arizona, New Mexico, w and n Texas, and w Oklahoma [20b.3c. Atriplex subg. Obione subsect. Argenteae, in part] Atriplex argentea
29 Leaf blades entire or remotely and irregularly dentate; other distribution > 30
30 Leaf blades mostly oblong, oblong-ovate, or elliptic to lanceolate, not subhastate or angled at base; Sacramento and San Joaquin valleys, e and s Coast Ranges, California [20b.3f. Atriplex subg. Obione subsect. Pusillae, in part] Atriplex coronata
30 Leaf blades variously shaped, at least some typically subhastate or angled at base, or if acute to obtuse at base (as in some A. argentea varieties) of different distribution; s British Columbia e to sw Manitoba, and s to e Washington, e Idaho, Nevada, se California, Utah, ne Arizona, nw New Mexico, n Texas [20b.3c. Atriplex subg. Obione subsect. Argenteae, in part] Atriplex argentea
31 Leaf blades linear, concolorous; bracteoles truncate apically; sw Wyoming, ne and c Utah, n, w, and sc Colorado [20b.3e. Atriplex subg. Obione subsect. Wolfianae] Atriplex wolfii
31 Leaf blades usually broader than linear, or if linear, abaxial surface much paler than adaxial and bracteoles not truncate; other distribution > 32
32 Leaf blades entire > 33
32 Leaf blades dentate, or if entire staminate glomerules mainly in terminal spikes > 36
33 Bracteole faces, at least some, conspicuously tuberculate or cristate [20b.3g. Atriplex subg. Obione subsect. Arenariae] > 34
33 Bracteole faces typically smooth, sometimes inconspicuously tuberculate > 35
34 Fruiting bracteoles (3.5-)4.5-7 × 3.5-5.6 mm, typically longer than broad, faces with or without appendages; plants coastal from New England s along Atlantic, and along Gulf to Texas Atriplex mucronata
34 Fruiting bracteoles 2.5-4.5 × 2.6-5 mm, typically as wide or wider than long, and with faces appendaged; plants coastal from North Carolina s along Atlantic and w along Gulf to coastal or near coastal w Texas Atriplex pentandra
35 Staminate glomerules all axillary Atriplex pacifica
35 Staminate glomerules mainly in terminal spikes Atriplex pentandra
36 Staminate glomerules axillary, or in very short, simple, terminal spikes [20b.3g. Atriplex subg. Obione subsect. Arenariae] > 37
36 Staminate glomerules in elongate, usually paniculate spikes > 38
37 Bracteole faces not appendaged; s California Atriplex serenana
37 Bracteole faces tuberculate, muricate, or cristate; coastal se and s United States w to Rio Grande, sw Texas Atriplex pentandra
38 Bracteoles 4-6 mm; leaf blades sinuate-dentate; Gulf of St. Lawrence, Prince Edward Island, Nova Scotia, and Quebec [20a.3. Atriplex sect. Sclerocalymma] Atriplex laciniata
38 Bracteoles 2-3.5 mm; leaf blades various, but if as above, of different distribution [20b.3g. Atriplex subg. Obione subsect. Arenariae] > 39
39 Leaves lanceolate to oblong, elliptic, or oval, subconcolorous; bracteole faces almost always conspicuously tuberculate; California and w Ne- vada Atriplex serenana
39 Leaves linear to lanceolate or oblong, white abaxially, green adaxially; bracteole faces usually unappendaged; s Arizona, s New Mexico and along Rio Grande, in Texas and Mexico Atriplex wrightii

Key 4 (20c. Atriplex subg. Pterochiton, for the most part)

1 Leaves sinuate-dentate to dentate or laciniate (at least some), or strongly undulate-crisped and appearing lobed; herbage silvery white > 2
1 Leaves entire or merely hastately lobed, or if sinuate-dentate or denticulate, herbage green or gray > 3
2 Leaf blades deeply, sharply dentate or laciniate; fruiting bracteoles orbiculate, entire to crenate, sessile, surfaces lacking processes; sw Utah, s Nevada, s California Atriplex hymenelytra
2 Leaf blades sinuate, sinuate-dentate, or hastate; fruiting bracteoles stipitate, 6-15 mm, macelike, surfaces often with elongate, radiating, hornlike, or flattened processes; se Arizona s New Mexico, along Rio Grande and Gulf Coast, w and s Texas Atriplex acanthocarpa
3 Bracteoles conspicuously longitudinally 4-winged, or with tubercles aligned in 4 parallel rows > 4
3 Bracteoles lacking lateral wings (tubercles sometimes aligned in 4 rows) > 7
4 Plants low, seldom more than 4 dm; subshrubs of playas in Great Basin and Range, or w Great Plains Atriplex gardneri
4 Plants low or tall; broad or various distribution > 5
5 Leaves mainly 2-3 mm wide and often over 2 cm, narrowly linear-elliptic, often rather acute apically; plants with very slender branchlets; s Arizona and s California Atriplex linearis
5 Leaves mostly 3-10+ mm wide, or if occasionally less then often less than 2 cm or of different distribution, or leaves spatulate, thickened, and obtuse apically; plants with branchlets not especially slender; various distribution > 6
6 Leaves mainly 0.3-0.8 cm wide; bract tip lacking lateral teeth; shrubs mainly 8-20 dm; widespread in w North America, from s Canada, southward in United States, mainly w of 100th meridian Atriplex canescens
6 Leaves often more than 8 mm wide; bract tip with or without lateral teeth; shrubs mainly 2-8 dm; se Utah and n Arizona Atriplex garrettii
7 Plants definitely spiny, branches terminating in thorns; bracteoles foliose, entire, united only at base, surfaces lacking appendages > 8
7 Plants not definitely spiny, or if somewhat so bracteoles at least 1/3 united, surfaces appendaged or not > 12
8 Bracteoles (4-)6-15 mm > 9
8 Bracteoles 2-4(-6) mm > 10
9 Leaves ovate to oval or elliptic, not hastate; body of bracteoles not constricted below free terminal valves; e Montana and sw North Dakota to Oregon, California, Arizona, New Mexico, and Texas Atriplex confertifolia
9 Leaves elongate-deltoid and commonly somewhat hastate; body of bracteoles constricted below terminal valves; w San Joaquin Valley and w Mojave Desert, California Atriplex spinifera
10 Leaves short petiolate to sessile, cordate basally, blade 0.5-1.5 cm; herbage silvery white; low shrubs Atriplex parryi
10 Leaves petiolate, truncate or cuneate basally, typically some subhastate; herbage grayish or greenish; shrubs to 20+ dm > 11
11 Twigs sharply angled, glabrous to sparingly puberulent; sw Utah, Ne- vada, s Arizona, s California Atriplex torreyi
11 Twigs terete, commonly puberulent; California, s Nevada, s Utah, and Arizona Atriplex lentiformis
12 Leaf blades typically some subhastate (except A. polycarpa, with many, tiny, commonly clustered leaves); shrubs to 30 dm; Utah sw to Mexico > 13
12 Leaf blades attenuate to rounded basally, seldom some subhastate; shrubs mainly less than 20 dm; various distribution > 15
13 Branchlets conspicuously and sharply angled; sw Utah, s Nevada, s Ari- zona, and s California Atriplex torreyi
13 Branchlets terete or nearly so; extending to Mexico > 14
14 Leaves 10-50 × 50 mm; sw Utah, Arizona, Nevada, California, Mexico Atriplex lentiformis
14 Leaves 3-15 (longer only on juvenile shoots) × 2-4 mm; s Nevada, sw Utah, Arizona, and Mexico from Sonora to Baja California Atriplex polycarpa
15 Leaves 2-4+ mm wide; bracteoles with appendages on basal 1/3; staminate flowers in spikes; plants prostrate; w Colorado, ne New Mexico, and e Utah Atriplex corrugata
15 Leaves often more than 4 mm wide; bracteoles with appendages various; staminate flowers mainly in panicles; plants not or seldom prostrate; distribution various or other > 16
16 Leaves dentate to denticulate or less commonly some or all entire; bracteoles somewhat rhomboid to orbicular; introduced, native to Australia, known in s California and s Arizona [20a.6 Atriplex sect. Dialysex] > 17
16 Leaves not simultaneously of above size and proportion; fruiting bracteoles various but not as above; w Great Plains and Intermountain region [20c. Atriplex subg. Pterochiton, in part] > 18
17 Leaves elliptic to oblong, often shortly hastate, and sometimes remotely denticulate; bracteoles somewhat rhomboid to semicircular in profile, biconvex, thickened and hard all over or with short papery valves; introduced in coastal s California Atriplex amnicola
17 Leaves rhomboid to orbicular, sinuate-dentate; fruiting bracteoles rhomboid to orbicular, papery all over or with thickened base; s California, s Arizona Atriplex nummularia
18 Leaves oblong-ovate to orbicular, more than 1 cm wide, proximalmost alternate; stems stiffly erect; staminate glomerules very numerous; se Utah south- ward through e Arizona, New Mexico, w Texas Atriplex obovata
18 Leaves linear to oblong, mainly less than 1 cm wide, or if wider, proximalmost opposite; stems prostrate to ascending, or less commonly erect; staminate glomerules numerous; Great Plains w to Great Basin and Colorado River drainage Atriplex gardneri