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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 2

1 Plants dioecious; leaves sessile, mostly opposite [20b.3i. Atriplex subg. Obione subsect. Californicae, for the most part]   (2)
+ Plants monoecious; leaves various, but if sessile and mostly opposite, of different distribution   (3)
2 (1) Leaves 2-5 mm, subequal to internodes; fruiting bracteoles 2-3 mm; coastal or near coastal s Texas and adjacent Mexico   46 Atriplex matamorensis
+ Leaves 8-25 mm, often surpassing internodes; fruiting bracteoles 4-8 mm; coastal Santa Barbara County, California, Baja California, Mexico   45 Atriplex watsonii
3 (1) 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]   44 Atriplex californica
+ Leaves subsessile to long petiolate, blade and fruiting bracteoles mostly more than 3 mm, but if shorter, not from coastal California   (4)
4 (3) Fruiting bracteoles (5-)6-12 mm, fibrous and spongy or merely spongy-thickened   (5)
+ Fruiting bracteoles mainly 3-6 mm, not fibrous or spongy thickened   (7)
5 (4) 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]   15 Atriplex holocarpa
+ Fruiting bracteoles variously shaped, bearing 1 or 2 appendages; different distributions   (6)
6 (5) 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]   43 Atriplex leucophylla
+ 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]   16 Atriplex lindleyi
7 (4) 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]   17 Atriplex semibaccata
+ Seeds monomorphic, either black or brown; bracts not fleshy; plants not low growing; leaf margin entire to dentate; various or other distribution   (8)
8 (7) Petioles to 1/2 as long as blades, or some blades typically more than 2.5 cm   (9)
+ Petioles short (much less than 1/2 as long as blades) or lacking, blades of various lengths   (10)
9 (8) 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]
+ 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   25 Atriplex argentea (in part)
10 (8) 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]   18 Atriplex suberecta (in part)
+ Leaves variously toothed or entire; fruiting bracteoles variously shaped and toothed; various or other distribution   (11)
11 (10) 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   42 Atriplex elegans (in part)
+ 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 (11) 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   37 Atriplex pentandra (in part)
+ 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 (12) 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   40 Atriplex coulteri
+ 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 (13) Staminate flowers in terminal spikes, pistillate ones in axillary clusters; Sacramento and San Joaquin valleys, California   41 Atriplex fruticulosa
+ 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   42 Atriplex elegans (in part)

List of Keys

  • List of lower taxa


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