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FNA | Family List | FNA Vol. 4 | Chenopodiaceae

20. Atriplex Linnaeus, Sp. Pl. 2: 1052. 1753; Gen. Pl. ed. 5, 472. 1754.

Orach, saltbush [ancient Latin name]

Stanley L. Welsh

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.

Species ca. 250 (62 in the flora): worldwide, mainly in subarctic, temperate, and subtropical regions.

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.


Bassett, I. J., C. W. Crompton, J. McNeill, and P. M. Taschereau. 1983. The Genus Atriplex (Chenopodiaceae) in Canada. Ottawa. [Agricu. Canada Monogr. 31.] Brown, G. D. 1956. Taxonomy of American Atriplex. Amer. Midl. Naturalist 55: 199-210. Hall, H. M. and F. E. Clements. 1923. The phylogenetic method in taxonomy: The North American species of Artemisia, Chrysothamnus, and Atriplex. Publ. Carnegie Inst. Wash. 326. Hanson, C. A. 1962. Perennial Atriplex of Utah and the Northern Deserts. M.S. thesis. Brigham Young University. McNeill, J., I. J. Bassett, C. W. Crompton, and P. M. Taschereau. 1983. Taxonomic and nomenclatural notes on Atriplex L. (Chenopodiaceae). Taxon 32: 549-556. Taschereau, P. M. 1972. Taxonomy and distribution of Atriplex species in Nova Scotia. Canad. J. Bot. 50: 1571-1594. Turesson, G. 1925. Studies in the genus Atriplex. Acta Univ. Lund, n. s. 21: 1-15. Welsh, S. L. 1995. Names and types of perennial Atriplex Linnaeus (Chenopodiaceae) in North America selectively exclusive of Mexico. Great Basin Naturalist 55: 322-334.

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)
+ Leaf blades not all dentate, some, or all, of them entire, leaves commonly opposite or subopposite at proximalmost nodes   (6)
2 (1) Fruiting bracteoles widest at middle, entire below middle, 2-4-toothed beyond middle; s California [20a.5. Atriplex sect. Semibaccata, in part]   18 Atriplex suberecta (in part)
+ Fruiting bracteoles mostly widest below middle, variously toothed, tuberculate, or entire; various or other distribution   (3)
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)
+ Leaves mainly ovate to lanceolate, acute to obtuse basally; various distribution [20a.3. Atriplex sect. Sclerocalymma]   (4)
4 (3) 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   12 Atriplex rosea
+ 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 (4) 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   13 Atriplex tatarica
+ 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   14 Atriplex laciniata (in part)
6 (1) 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].....   22 Atriplex suckleyi
+ 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 (6) 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]   21 Atriplex pleiantha
+ 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 (7) Bracteoles on stipes 2-6 mm, body 5-6 mm thick, globose, with hornlike ap- pendages on both faces; se Utah   24 Atriplex saccaria (in part)
+ Bracteoles variously sessile or, if stipitate, not otherwise as above   (9)
9 (8) 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   23 Atriplex graciliflora
+ 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 (9) 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]   42 Atriplex elegans (in part)
+ Fruiting bracteoles not orbicular, or if so, never radiately dentate to base and not at once strongly compressed; other distribution   (11)
11 (10) Leaf blades oval to ovate or ovate-lanceolate, hastate or not; w Nevada and Great Valley of California   (12)
+ Leaf blades variously shaped, if as above, mainly of other distribution   (13)
12 (11) 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]   47 Atriplex phyllostegia
+ 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]   48 Atriplex covillei
13 (11) 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]   27 Atriplex klebergorum
+ Bracteoles less than 4-6 mm wide, or if that wide, then differing otherwise or of other distribution   (14)
14 (13) 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)
+ 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 (14) Leaves and/or branches opposite, at least proximalmost [20b.3f. Atriplex subg. Obione subsect. Pusillae, in part]   (16)
+ Leaves and branches all alternate   (18)
16 (15) Plants tending to sprawl, with leaves and foliose bracts tending to recurve   31 Atriplex parishii (in part)
+ Plants erect or ascending, with leaves and foliose bracts straight or nearly so   (17)
17 (16) 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   33 Atriplex tularensis
+ 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   34 Atriplex coronata (in part)
18 (15) 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]   26 Atriplex powellii (in part)
+ Fruiting bracteoles not at once as above; various or other distribution [20b.3f. Atriplex subg. Obione subsect. Pusillae, for the most part]   (19)
19 (18) Leaf blades of at least some proximalmost leaves cordate at base; nc and c California   32 Atriplex cordulata (in part)
+ Leaf blades rounded to acute or at most subcordate at base; various distribution   (20)
20 (19) Branches copiously villous, at least around inflorescence   31 Atriplex parishii (in part)
+ Branches merely scurfy   (21)
21 (20) Faces of bracteoles tuberculate   (22)
+ Faces of bracteoles smooth   (23)
22 (21) 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]   29 Atriplex wolfii (in part)
+ 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   31 Atriplex parishii (in part)
23 (21) Bracteoles 2-3 mm, subhastate, denticulate, or crenulate; stems mainly not suffused with red; c valley of California southward   31 Atriplex parishii (in part)
+ Bracteoles 1-2 mm, ovate, entire; stems suffused with red; ne California, se Oregon, Nevada   30 Atriplex pusilla
24 (14) 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)
+ Leaf blades neither deltoid nor ovate, usually broadest at or beyond middle, in few species leaves broadest at base and conspicuously dentate   (31)
25 (24) 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]   24 Atriplex saccaria (in part)
+ Leaf blades never cordate at base or, in some, sessile distal ones sometimes cordate-clasping; fruiting bracteoles all similar on same plant   (26)
26 (25) 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]   26 Atriplex powellii (in part)
+ Bracteoles not panduriform; leaf blades not conspicuously 3-veined   (27)
27 (26) Bracteoles broadly rhombic, toothed beyond middle; Sacramento and San Joaquin valleys, California [20.b.3f. Atriplex subg. Obione subsect. Pusillae, in part]   32 Atriplex cordulata (in part)
+ Bracteoles of various shapes and teeth various; various or other distribution   (28)
28 (27) 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]   28 Atriplex truncata
+ Bracteoles dentate well below apex, often to base, large; other distribution   (29)
29 (28) 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]   25 Atriplex argentea (in part)
+ Leaf blades entire or remotely and irregularly dentate; other distribution   (30)
30 (29) 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]   34 Atriplex coronata (in part)
+ 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]   25 Atriplex argentea (in part)
31 (24) 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]   29 Atriplex wolfii (in part)
+ Leaf blades usually broader than linear, or if linear, abaxial surface much paler than adaxial and bracteoles not truncate; other distribution   (32)
32 (31) Leaf blades entire   (33)
+ Leaf blades dentate, or if entire staminate glomerules mainly in terminal spikes   (36)
33 (32) Bracteole faces, at least some, conspicuously tuberculate or cristate [20b.3g. Atriplex subg. Obione subsect. Arenariae]   (34)
+ Bracteole faces typically smooth, sometimes inconspicuously tuberculate   (35)
34 (33) 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   38 Atriplex mucronata
+ 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   37 Atriplex pentandra (in part)
35 (33) Staminate glomerules all axillary   39 Atriplex pacifica
+ Staminate glomerules mainly in terminal spikes   37 Atriplex pentandra (in part)
36 (32) Staminate glomerules axillary, or in very short, simple, terminal spikes [20b.3g. Atriplex subg. Obione subsect. Arenariae]   (37)
+ Staminate glomerules in elongate, usually paniculate spikes   (38)
37 (36) Bracteole faces not appendaged; s California   35 Atriplex serenana (in part)
+ Bracteole faces tuberculate, muricate, or cristate; coastal se and s United States w to Rio Grande, sw Texas   37 Atriplex pentandra (in part)
38 (36) Bracteoles 4-6 mm; leaf blades sinuate-dentate; Gulf of St. Lawrence, Prince Edward Island, Nova Scotia, and Quebec [20a.3. Atriplex sect. Sclerocalymma]   14 Atriplex laciniata (in part)
+ Bracteoles 2-3.5 mm; leaf blades various, but if as above, of different distribution [20b.3g. Atriplex subg. Obione subsect. Arenariae]   (39)
39 (38) Leaves lanceolate to oblong, elliptic, or oval, subconcolorous; bracteole faces almost always conspicuously tuberculate; California and w Ne- vada   35 Atriplex serenana (in part)
+ 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   36 Atriplex wrightii

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