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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 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)
+ Leaves entire or merely hastately lobed, or if sinuate-dentate or denticulate, herbage green or gray   (3)
2 (1) Leaf blades deeply, sharply dentate or laciniate; fruiting bracteoles orbiculate, entire to crenate, sessile, surfaces lacking processes; sw Utah, s Nevada, s California   54 Atriplex hymenelytra
+ 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   49 Atriplex acanthocarpa
3 (1) Bracteoles conspicuously longitudinally 4-winged, or with tubercles aligned in 4 parallel rows   (4)
+ Bracteoles lacking lateral wings (tubercles sometimes aligned in 4 rows)   (7)
4 (3) Plants low, seldom more than 4 dm; subshrubs of playas in Great Basin and Range, or w Great Plains   51 Atriplex gardneri (in part)
+ Plants low or tall; broad or various distribution   (5)
5 (4) 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   62 Atriplex linearis
+ 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 (5) 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   61 Atriplex canescens
+ Leaves often more than 8 mm wide; bract tip with or without lateral teeth; shrubs mainly 2-8 dm; se Utah and n Arizona   53 Atriplex garrettii
7 (3) Plants definitely spiny, branches terminating in thorns; bracteoles foliose, entire, united only at base, surfaces lacking appendages   (8)
+ Plants not definitely spiny, or if somewhat so bracteoles at least 1/3 united, surfaces appendaged or not   (12)
8 (7) Bracteoles (4-)6-15 mm   (9)
+ Bracteoles 2-4(-6) mm   (10)
9 (8) 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   56 Atriplex confertifolia
+ Leaves elongate-deltoid and commonly somewhat hastate; body of bracteoles constricted below terminal valves; w San Joaquin Valley and w Mojave Desert, California   57 Atriplex spinifera
10 (8) Leaves short petiolate to sessile, cordate basally, blade 0.5-1.5 cm; herbage silvery white; low shrubs   60 Atriplex parryi
+ Leaves petiolate, truncate or cuneate basally, typically some subhastate; herbage grayish or greenish; shrubs to 20+ dm   (11)
11 (10) Twigs sharply angled, glabrous to sparingly puberulent; sw Utah, Ne- vada, s Arizona, s California   59 Atriplex torreyi (in part)
+ Twigs terete, commonly puberulent; California, s Nevada, s Utah, and Arizona   58 Atriplex lentiformis (in part)
12 (7) Leaf blades typically some subhastate (except A. polycarpa, with many, tiny, commonly clustered leaves); shrubs to 30 dm; Utah sw to Mexico   (13)
+ Leaf blades attenuate to rounded basally, seldom some subhastate; shrubs mainly less than 20 dm; various distribution   (15)
13 (12) Branchlets conspicuously and sharply angled; sw Utah, s Nevada, s Ari- zona, and s California   59 Atriplex torreyi (in part)
+ Branchlets terete or nearly so; extending to Mexico   (14)
14 (13) Leaves 10-50 × 50 mm; sw Utah, Arizona, Nevada, California, Mexico   58 Atriplex lentiformis (in part)
+ Leaves 3-15 (longer only on juvenile shoots) × 2-4 mm; s Nevada, sw Utah, Arizona, and Mexico from Sonora to Baja California   55 Atriplex polycarpa
15 (12) 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   52 Atriplex corrugata
+ 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 (15) 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)
+ 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 (16) 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   20 Atriplex amnicola
+ Leaves rhomboid to orbicular, sinuate-dentate; fruiting bracteoles rhomboid to orbicular, papery all over or with thickened base; s California, s Arizona   19 Atriplex nummularia
18 (16) 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   50 Atriplex obovata
+ 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   51 Atriplex gardneri (in part)

List of Keys

  • List of lower taxa


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