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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 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]   1 Atriplex hortensis
+ 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 (1) Bracteoles ± thickened with spongy tissue, especially toward base [20a.2. Atriplex sect. Teutliopsis]   (3)
+ Bracteoles not thickened (except A. joaquiniana)   (7)
3 (2) 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)
+ Lower leaves (sometimes all or most) triangular and thin textured   (5)
4 (3) 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   2 Atriplex littoralis
+ 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   8 Atriplex dioica (in part)
5 (3) 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   10 Atriplex glabriuscula (in part)
+ Bracteoles all sessile, margin entire or slightly toothed, lateral angles shortly pointed but not definitely toothed; geography below   (6)
6 (5) 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   10 Atriplex glabriuscula (in part)
+ 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   9 Atriplex prostrata
7 (2) 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   11 Atriplex nudicaulis
+ Plants mostly more than 1.2 dm; proximal leaves, bracteoles, and seeds not simultaneously as above; distribution various   (8)
8 (7) Fruiting bracteoles ovate to elliptic or orbiculate-cordate   (9)
+ Fruiting bracteoles never orbiculate-cordate, frequently toothed, usually with lateral angles   (11)
9 (8) Bracteoles ovate to widely triangular, surfaces often 2-tuberculate, margin toothed; leaves usually thickened, ± scurfy, even at maturity   8 Atriplex dioica (in part)
+ Bracteoles orbiculate-ovate, surfaces smooth, margin entire; leaves usually thin, green on both sides, not or scarcely scurfy   (10)
10 (9) Leaves broadly triangular-hastate; widely distributed from Quebec, w to Brit- ish Columbia and s to California, Nevada, Utah, and Colorado   7 Atriplex heterosperma
+ Leaves mostly lanceolate to narrowly hastate; s British Columbia, adjacent Alberta, and South Dakota   4 Atriplex oblongifolia (in part)
11 (8) 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   6 Atriplex joaquiniana
+ 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 (11) Largest bracteoles strap-shaped or ovate-lanceolate; halophytes of w and nw coastal areas of North America   5 Atriplex gmelinii
+ Largest bracteoles ovate, ovate-triangular, or rhombic; e coastal North America (disjunctly westward) or widespread ruderal weeds   (13)
13 (12) Radicle of brown seeds basal and spreading; e coastal salt marshes and disjunctly w to Hudson Bay and n Alberta   10 Atriplex glabriuscula (in part)
+ Radicle of brown seeds subbasal to median and antrorse; widespread ruderal weeds   (14)
14 (13) Bracteoles rhombic, margin united almost to middle, lateral angles definite; terminal inflorescence with densely compressed, ± uniform- sized bracteoles; distal leaves green on both sides   3 Atriplex patula
+ 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   4 Atriplex oblongifolia (in part)

List of Keys

  • List of lower taxa


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