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)