1	Ovaries and capsules ± hairy		(2)
+	Ovaries and capsules glabrous		(38)
2 (1)	Cyathia in capitate glomerules (with reduced, bractlike leaves subtending cyathia)		(3)
+	Cyathia solitary or in small, cymose clusters at distal nodes, on congested, axillary branches, or at branch tips		(6)
3 (2)	Stipules distinct when young, connate into deltate scales when older, often with dark glands along margins or at base; styles 0.6–0.9 mm; seeds plumply ovoid, 0.7–0.8 mm wide, dark reddish brown to almost black; s Florida.		54 Euphorbia lasiocarpa
+	Stipules distinct or connate only at base, deltate, subulate, or linear- or filiform-subulate, without dark glands along margins or at base; styles 0.1–0.6 mm; seeds narrowly ovoid or ovoid-oblong, 0.5–0.7 mm wide, not dark reddish brown to almost black; widespread, including s Florida		(4)
4 (3)	Glomerules of cyathia terminal and axillary, axillary glomerules sessile or at tips of elongated, leafless stalks		45 Euphorbia hirta
+	Glomerules of cyathia terminal, on main stems or short, leafy, axillary branches, with reduced, bractlike leaves subtending cyathia		(5)
5 (4)	Stems glabrous, strigillose, or pilose; involucre 0.8–1.6 × 0.7–1.3 mm, appendages 0.2–1.1 × 0.5–1.7 mm; styles 0.4–0.6 mm; capsules pilose; seeds 0.9–1.5 mm.		30 Euphorbia capitellata (in part)
+	Stems usually both strigillose and hirsute; involucre 0.5–0.7 × 0.4–0.6 mm, appendages 0.1–0.2 × 0.1–0.3 mm; styles 0.1–0.3 mm; capsules strigillose; seeds 0.7–0.9(–1.1) mm.		65 Euphorbia ophthalmica
6 (2)	Involucral gland appendages unequal		(7)
+	Involucral gland appendages ± equal in size or rudimentary to absent		(11)
7 (6)	Seeds 3-angled to almost round in cross section, with 4–5 rounded, transverse ridges encircling seed; Arizona, California.		68 Euphorbia pediculifera (in part)
+	Seeds conspicuously 4-angled in cross section, variously grooved or ridged, but not with 4–5 rounded, transverse ridges encircling seed; Florida, Louisiana (E. conferta, E. pergamena, and E. thymifolia) or sw United States (E. indivisa)		(8)
8 (7)	Styles 0.8–1.3 mm, usually unbranched, rarely 2-fid at apex; sw United States from Arizona to Texas.		50 Euphorbia indivisa
+	Styles 0.4–1 mm, 2-fid; Florida, Louisiana		(9)
9 (8)	Stems pilose.		34 Euphorbia conferta
+	Stems strigose to sericeous or strigose-tomentulose		(10)
10 (9)	Capsules well exserted from involucre at maturity; seeds with 3 or 4 transverse sulci alternating with low transverse ridges.		70 Euphorbia pergamena
+	Capsules scarcely exserted from involucre, base often remaining inside the involucre and splitting one side of it during maturity; seeds with 4 low transverse ridges, but not sulcate.		85 Euphorbia thymifolia (in part)
11 (6)	Leaf margins toothed, at least toward apex		(12)
+	Leaf margins entire (rarely sparsely serrulate in E. garberi and E. laredana)		(20)
12 (11)	Styles unbranched		(13)
+	Styles 2-fid		(14)
13 (12)	Stems strigillose; seeds broadly ovoid, 1.2–1.4 × 1–1.1 mm, with 2 well-defined transverse ridges.		76 Euphorbia rayturneri
+	Stems pilose to lanate; seeds narrowly oblong-ovoid to ellipsoid, 1–1.5 × 0.5–0.6 mm, almost smooth, rugulose, dimpled, or with short and irregularly interrupted furrows (seeds appearing partially and irregularly few-ridged).		83 Euphorbia stictospora
14 (12)	Capsules with pubescence concentrated along keels or toward base, often glabrous between keels		(15)
+	Capsules ± evenly hairy or pubescence at least not concentrated only along keels and base, not glabrous between keels		(16)
15 (14)	Petioles, leaf blade abaxial surfaces, ovaries, and capsules glabrous or sparsely sericeous, pilose, or villous; seeds reddish brown to orange or gray-pink, almost smooth or with faint transverse ridges; s Florida		59 Euphorbia mendezii
+	Petioles, leaf blade abaxial surfaces, ovaries, and capsules crisped-villous to glabrate; seeds white but with barely concealed brown surface beneath, with sharp transverse ridges; widespread, including s Florida.		75 Euphorbia prostrata
16 (14)	Capsules pilose to villous		(17)
+	Capsules strigose to sericeous		(18)
17 (16)	Involucral gland appendages not puberulent-ciliate along margins; capsule 1.4–1.9 × 1.5–2 mm; seeds ovoid to narrowly ovoid, 1–1.4 × 0.6–0.9 mm; California.		79 Euphorbia serpillifolia (in part)
+	Involucral gland appendages often puberulent-ciliate along margins; capsule 1.5–1.9 × 1.3–1.7 mm; seeds narrowly pyramidal-ovoid, 1.1–1.3 × 0.4–0.6 mm; Texas.		88 Euphorbia velleriflora
18 (16)	Capsules scarcely exserted from involucre, base often remaining inside involucre and splitting one side of it during maturity.		85 Euphorbia thymifolia (in part)
+	Capsules well exserted from involucre at maturity		(19)
19 (18)	Stems rooting at nodes; styles 0.5–0.8 mm; seeds bluntly angled, smooth or papillate.		47 Euphorbia humistrata
+	Stems not rooting at nodes; styles 0.3–0.4 mm; seeds sharply angled, with 3–4 low transverse ridges.		56 Euphorbia maculata
20 (11)	Capsules with pubescence concentrated along keels or toward base, often glabrous or less hairy between keels.		53 Euphorbia laredana
+	Capsules ± evenly hairy or pubescence at least not concentrated only along keels and base, not glabrous between keels		(21)
21 (20)	Involucral gland appendages divided into 3–8 triangular to subulate segments		(22)
+	Involucral gland appendages entire, toothed, or absent		(23)
22 (21)	Shrubs; stems ascending, puberulent to shortly hirsute; stipules 0.3–0.5 mm; seeds 1.4–1.5 mm.		51 Euphorbia jaegeri
+	Annual herbs; stems prostrate, villous, hairs glandular-glistening; stipules rudimentary to 0.2 mm; seeds 0.8–1 mm.		81 Euphorbia setiloba
23 (21)	Proximal leaf blades ovate to ovate-elliptic, distal ones linear to elliptic-linear, more than 6 times as long as wide.		25 Euphorbia angusta
+	Leaf blades not linear (rarely linear in E. pediculifera), less than 3 times as long as wide		(24)
24 (24)	Stems glabrous or sparsely hairy 37. Euphorbia deltoidea (in part)		(24)
+	Stems conspicuously and densely hairy		(25)
25 (24)	Stems with appressed hairs		(26)
+	Stems with spreading to erect hairs		(32)
26 (25)	Leaf blade apices long-acuminate and spinulose; seeds 2.2–2.6 mm.		23 Euphorbia acuta
+	Leaf blade apices acute to obtuse or rounded; seeds 0.8–1.8(–2) mm		(27)
27 (26)	Largest leaf blades usually more than 15 mm; seeds 3-angled to almost round in cross section, with 4–5 rounded, transverse ridges encircling seed.		68 Euphorbia pediculifera (in part)
+	Largest leaf blades less than 15 mm; seeds 3- or 4-angled in cross section, without 4–5 rounded, transverse ridges encircling seed		(28)
28 (27)	Involucral glands deep red, purple, or purple-black		(29)
+	Involucral glands green to yellow-green or brown		(30)
29 (28)	Involucral gland appendages absent or forming narrow rim around distal margin of gland, 0–0.1 × 0–0.6 mm; seeds ovoid, 1–1.4 × 0.6–0.8 mm; Texas.		33 Euphorbia cinerascens
+	Involucral gland appendages oblong to flabellate, 0.4–0.7(–1) × 0.7–1.2 mm; seeds narrowly oblong, 1–1.2 × 0.4–0.6 mm; Arizona, California.		58 Euphorbia melanadenia
30 (28)	Stipules filiform, 0.8–1.3 mm; involucres 2–2.5 × 2.2–2.6 mm; styles 0.8–1.2 mm; capsules 1.9–2.3 × 2–2.4 mm; seeds whitish, 1.5–1.8(–2) × 0.6–0.9 mm; c, s United States but not Florida.		55 Euphorbia lata
+	Stipules triangular or triangular-subulate, 0.2–0.7 mm; involucres 0.6–1 × 0.5–1.3 mm; styles 0.3–0.7 mm; capsules 1.1–1.6 × 1.3–2.2 mm; seeds gray to reddish brown, 0.8–1.2 × 0.5–0.8 mm; s Florida		(31)
31 (30)	Stems wiry, less than 1 mm diam., 5–20 cm; leaf blades deltate, 2–5(–7) × 1–4.5 mm.		37 Euphorbia deltoidea (in part)
+	Stems not wiry, 1–3 mm diam., 15–50 cm; leaf blades ovate to oblong-elliptic, 4–9(–15) × 3–6 mm.		40 Euphorbia garberi (in part)
32 (25)	Stems and leaves with glistening hairs; stipules (0–)0.1 mm.		26 Euphorbia arizonica
+	Stems and leaves without glistening hairs; stipules 0.2–1.6 mm		(33)
33 (32)	Involucres 0.4–0.6 × 0.5–0.9 mm, glands 0.1 × 0.1–0.2 mm, appendages absent.		61 Euphorbia micromera (in part)
+	Involucres 0.6–2.5 × 0.5–2.4 mm, glands 0.1–0.6 × 0.2–0.9 mm, appendages usually present (absent or forming narrow rim in some specimens of E. deltoidea; sometimes forming narrow rim in E. polycarpa)		(34)
34 (33)	Involucral gland appendages ciliate-puberulent adaxially; perennial herbs.		87 Euphorbia vallis-mortae
+	Involucral gland appendages not ciliate-puberulent adaxially; annual or perennial herbs		(35)
35 (34)	Seeds 1.1–1.7 × 0.8–1.3 mm.		64 Euphorbia ocellata (in part)
+	Seeds 0.8–1.2 × 0.5–0.8 mm		(36)
36 (35)	Stems prostrate to ascending, mat-forming; sw United States.		72 Euphorbia polycarpa (in part)
+	Stems ascending to erect, not mat-forming; s Florida		(37)
37 (36)	Stems and leaves villous or villous-hirsute; stems ascending to erect, wiry, less than 1 mm diam., 5–20 cm; leaf blades deltate, 2–4.5 × 2–4.5 mm.		37 Euphorbia deltoidea (in part)
+	Stems and leaves canescent; stems ascending, not wiry, 1–3 mm diam., 15–50 cm; leaf blades ovate to oblong-elliptic, 4–9(–15) × 3–6 mm.		40 Euphorbia garberi (in part)
38 (1)	Leaf blades linear, 5 times or more as long as wide, bases symmetric or subsymmetric (sometimes slightly asymmetric in E. parryi)		(39)
+	Leaf blades not linear, 4 times or less as long as wide, bases usually asymmetric, rarely subsymmetric to symmetric		(43)
39 (38)	Leaf blade margins serrulate.		39 Euphorbia florida
+	Leaf blade margins entire		(40)
40 (39)	Stipules entire; seeds 0.9–1.4 mm, 4-angled in cross section		(41)
+	Stipules usually deeply and irregularly fringed, lobed, or lacerate and divided into slender segments, rarely entire; seeds 1.4–2 mm, bluntly 3-angled or rounded-angular in cross section		(42)
41 (40)	Stipules 0.3–0.5 mm; involucres 0.4–0.5 mm, glands yellow to pink; styles 2-fid; capsules 1.1–1.4 × 1.1–1.4 mm; s Arizona.		44 Euphorbia gracillima
+	Stipules 0.5–0.9 mm; involucres 0.7–0.9 mm, glands pink to dark purple; styles unbranched; capsules 1.5–1.8 × 1.6–1.8 mm; sw United States, including s Arizona.		77 Euphorbia revoluta
42 (40)	Stems erect or ascending; involucral gland appendages 0.4–2.5 × 1.1–1.7 mm.		62 Euphorbia missurica (in part)
+	Stems usually prostrate, rarely ascending-erect; involucral gland appendages 0.2–0.6 × 0.3–0.7(–1.1) mm.		67 Euphorbia parryi
43 (38)	Styles unbranched		(44)
+	Styles 2-fid at least toward apex		(46)
44 (43)	Annual herbs with slender taproots; leaf blade margins serrulate to denticulate; styles filiform, 1.8–2.6 mm; California.		46 Euphorbia hooveri
+	Perennial herbs with thickened taproots; leaf blade margins entire; styles thickened-clavate, 0.3–0.5 mm; Texas		(45)
45 (44)	Petioles 0–0.2(–0.3) mm; leaf blade bases cordate to auriculate; involucral gland appendages 0.1–0.2(–0.5) × 0.4–0.8 mm, entire or dentate-crenate.		27 Euphorbia astyla
+	Petioles 0.3–0.9 mm; leaf blade bases rounded to truncate; involucral gland appendages 0.3–0.6 × 0.8–1.2 mm, usually deeply dissected into 4–5 acuminate lobes, rarely entire or crenate.		52 Euphorbia jejuna
46 (43)	Cyathia in capitate glomerules (with reduced, bractlike leaves subtending cyathia)		(47)
+	Cyathia solitary or in small cymose clusters at distal nodes or on congested, axillary branches		(48)
47 (46)	Stipules distinct, filiform or divided into subulate-filiform segments; leaf blades ovate to narrowly ovate, often with red spot in center, 4–19 × 2–8 mm; stems and leaves glabrous, strigillose or pilose.		30 Euphorbia capitellata (in part)
+	Stipules connate, deltate, entire; leaf blades obliquely oblong-oblanceolate, 10–35 × 7–15 mm; stems and leaves glabrous.		48 Euphorbia hypericifolia
48 (46)	Leaf blade margins toothed (at least toward apex or on majority of leaves)		(49)
+	Leaf blade margins entire (occasionally toothed in E. blodgettii; rarely sparsely serrate in E. porteriana)		(59)
49 (48)	Seeds with prominent transverse ridges that interrupt abaxial keel		(50)
+	Seeds without prominent transverse ridges, or if present, not interrupting abaxial keel		(51)
50 (49)	Stems shortly pilose or puberulent proximally (often glabrous distally); capsules 1.3–1.5 × 1.1–1.5 mm.		22 Euphorbia abramsiana
+	Stems glabrous; capsules 1.3–1.9 × 1.6–2 mm.		42 Euphorbia glyptosperma
51 (49)	Largest leaf blades more than 20 mm		(52)
+	Largest leaf blades less than 20 mm		(54)
52 (51)	Seeds 1.9–2.3 × 1.3–1.4 mm; stems and leaves glabrous.		86 Euphorbia trachysperma
+	Seeds 1–1.6 × 0.5–1.1 mm; stems and leaves glabrous or hairy		(53)
53 (52)	Stems sparsely to densely pilose or pilose-crinkled proximally, usually glabrous distally; leaf blades glabrous or sparsely pilose toward base (abaxially), glabrous (adaxially); seeds with prominent transverse ridges or coarsely and inconspicuously pitted-reticulate.		49 Euphorbia hyssopifolia
+	Stems sparsely to moderately pilose to villous or with short, incurved hairs, pubescence often concentrated at nodes and distally (hairs occasionally in 2 bands along opposite sides of stem); leaf blades usually sparsely to moderately pilose, especially toward base, sometimes glabrous; seeds finely and irregularly wrinkled or with indistinct shallow, rounded cross ridges.		63 Euphorbia nutans
54 (51)	Leaf blade surfaces papillate; cocci of capsule often elongated and terminating in empty portion.		90 Euphorbia villifera (in part)
+	Leaf blade surfaces not papillate; cocci of capsule not elongated or terminating in empty portion		(55)
55 (54)	Stem and leaves glabrous		(56)
+	Stem and leaves usually hairy, rarely glabrate		(57)
56 (55)	Seeds pyramidal to oblong-ovoid, weakly 4-angled in cross section, 0.9–1 × 0.7 mm, reddish brown to brown, minutely beaded, with broad, rounded, transverse ridges; s coastal Louisiana and adjacent Texas.		57 Euphorbia meganaesos
+	Seeds ovoid to narrowly ovoid, 4-angled in cross section, 1–1.4 × 0.6–0.9 mm, pink, light brown or grayish, smooth to dimpled or rugose, or with faint transverse ridges; widespread, but not coastal Louisiana and adjacent Texas.		79 Euphorbia serpillifolia (in part)
57 (55)	Leaf blade margins serrate to serrulate, usually with conspicuous teeth at base; capsules 2–2.6 × 3.2–3.7 mm; seeds 1.5–1.8 × 1.1–1.3(–1.5) mm.		80 Euphorbia serrula
+	Leaf blade margins usually entire in proximal 1/2 and serrulate in distal 1/2 (rarely some leaves with margins nearly entire in E. vermiculata; rarely some leaves serrulate nearly to base in E. serpillifolia); capsules 1.4–1.9 × 1.5–2.1 mm; seeds 1–1.4 × 0.6–0.9 mm		(58)
58 (57)	Stems prostrate to ascending, often mat-forming; cyathial glands yellow to pink; seeds smooth to dimpled or rugose, or with faint transverse ridges; California.		79 Euphorbia serpillifolia (in part)
+	Stems prostrate to ascending or erect, not mat-forming; cyathial glands red to reddish green; seeds rugulose and sometime also with low transverse ridges; Arizona, New Mexico, ne United States, Canada.		89 Euphorbia vermiculata
59 (48)	Stipules (at least those of upper side of stem) connate, forming deltate, ligulate, or ovate scale		(60)
+	Stipules usually distinct, occasionally connate basally (rarely connate to middle in E. platysperma), not forming conspicuous, deltate, ligulate, or ovate scale		(63)
60 (59)	Subshrubs or shrubs; stems erect to ascending; leaf blade bases slightly asymmetric.		60 Euphorbia mesembrianthemifolia
+	Herbs; stems prostrate to decumbent and often rooting at nodes; leaf blade bases asymmetric		(61)
61 (60)	Perennials; involucral glands 0.2–0.5 × (0.2–)0.3–0.8 mm, appendages 0.3–1 × 0.6–1.3 mm; leaf blades often with red blotch in center.		24 Euphorbia albomarginata
+	Annuals, rarely short-lived perennials; involucral glands 0.1 x 0.1–0.3 mm, appendages 0–0.2 × 0.1–0.3 mm; leaf blades without red blotch		(62)
62 (61)	Stems prostrate to decumbent; involucral gland appendages unequal (pair near sinus lunate to oblong, 0.1–0.2 × 0.1–0.3 mm, distal margins entire, crenulate, or irregularly sinuate, other pair rudimentary, 0–0.1 × 0.1–0.3 mm, distal margins crenulate or entire); peninsular Florida.		28 Euphorbia blodgettii
+	Stems prostrate; involucral gland appendages equal, forming narrow rim at edge of gland, 0.1–0.2 × 0.2–0.3 mm, distal margins entire or crenulate; widespread, including peninsular Florida.		78 Euphorbia serpens
63 (59)	Perennial herbs or subshrubs with thickened and often woody rootstocks		(64)
+	Annual, rarely short-lived perennial, herbs with taproots or spreading rootstocks		(70)
64 (63)	Seeds 1.6–2.4 mm		(65)
+	Seeds 0.8–1.4 mm		(67)
65 (64)	Capsules 2.8–3.3 × 2.8–3.4 mm; involucres broadly campanulate to hemispheric, 1.7–2.2 × 1.5–2.7 mm; styles 0.7–0.9 mm; leaf blades ovate or orbiculate-deltate to reniform-deltate, 5–17 × 4–16 mm.		69 Euphorbia perennans
+	Capsules 1.7–2.4 × 1.6–2.5 mm; involucres campanulate to turbinate or broadly cupulate, 0.8–1.7 × 0.8–1.8 mm; styles 0.3–0.4 mm; leaf blades lanceolate, linear- or oblong-lanceolate, ovate, or orbiculate, 3–11 × 0.8–7 mm		(66)
66 (65)	Stems usually erect, rarely slightly decumbent; leaf blades ovate to lanceolate or oblong- or linear-lanceolate, 3–11 × 0.8–3(–5) mm, apex acute to short acuminate, base short-tapered, occasionally one side rounded.		Euphorbia chaetocalyx
+	Stems usually prostrate, decumbent, or ascending, very rarely erect; leaf blades usually orbiculate to ovate, rarely almost lanceolate, 3–8 × 2.5–7 mm, apex rounded to obtuse, base slightly cordate to rounded or obtuse.		38 Euphorbia fendleri
67 (64)	Stipules usually glabrous (occasionally sparsely hairy with appressed uncinate hairs in E. deltoidea)		(68)
+	Stipules pilose to hirsute		(69)
68 (67)	Stems prostrate; stems and leaf blades glabrous or sparsely hairy with appressed uncinate hairs; s Florida.		37 Euphorbia deltoidea (in part)
+	Stems erect to ascending; stems and leaf blades usually villous, rarely glabrous; Texas.		90 Euphorbia villifera (in part)
69 (67)	Capsules 1.6–1.7 × 1.6–1.9 mm; seeds 1.2–1.4 mm; involucral gland appendages absent; involucres 1–1.4 mm.		66 Euphorbia parishii
+	Capsules 1.1–1.4 × 1.1–1.4 mm; seeds 0.8–1.1 mm; involucral gland appendages present, occasionally forming rim at margin of gland; involucres 0.6–1.1 mm.		72 Euphorbia polycarpa (in part)
70 (63)	Capsules 4.7–5.5(–6) mm; seeds (2.8–)4.1–5.2 mm, bottle-shaped, strongly dorsiventrally compressed and weakly 3-angled in cross section, with linear carunclelike structure.		31 Euphorbia carunculata
+	Capsules 1–3.5(–4) mm; seeds 0.7–2.8 mm, not bottle-shaped, weakly dorsiventrally compressed or terete to sub-, 3-, or 4-angled in cross section, without carunclelike structure		(71)
71 (70)	Seeds terete or bluntly subangled in cross section (weakly dorsiventrally compressed in E. platysperma and E. polygonifolia, thus appearing semielliptic), usually smooth, occasionally rugose, minutely pitted, or obscurely wrinkled (E. platysperma with sharp, linelike, longitudinal ridges on adaxial side)		(72)
+	Seeds usually 3–4-angled in cross section (± weakly angled in E. villifera), smooth to rugose or wrinkled, or with transverse ridges		(78)
72 (71)	Seeds (2–)2.2–2.8 mm, weakly dorsiventrally compressed in cross section		(73)
+	Seeds 0.7–2.1 mm, terete to bluntly sub- or 3-angled in cross section		(74)
73 (72)	Involucral gland appendages present; leaf blade apices usually acute to mucronulate, rarely obtuse; capsules 2.7–3.2 × 2.2–2.9 mm; Arizona, California.		71 Euphorbia platysperma
+	Involucral gland appendages absent; leaf blade apices obtuse, often mucronulate; capsules 3–3.5(–4) × (2–)2.4–3 mm; Atlantic and Great Lakes shores.		73 Euphorbia polygonifolia
74 (72)	Stems erect or ascending; leaf blades narrowly oblong to narrowly lanceolate-oblong; styles 0.5–1.4 mm; involucral gland appendages present, 0.4–2.5 mm; seeds bluntly 3-angled.		62 Euphorbia missurica (in part)
+	Stems prostrate to slightly ascending; leaf blades oblong, oblong-obovate, narrowly elliptic, or lanceolate, ovate, deltate or falcate; styles 0.2–0.6 mm; involucral gland appendages present or absent, (0–)0.1–1 mm; seeds terete to bluntly subangled		(75)
75 (74)	Leaf blades ovate to deltate or falcate; w United States.		64 Euphorbia ocellata (in part)
+	Leaf blades elliptic, oblong, or lanceolate; c United States to Gulf and Atlantic coasts		(76)
76 (75)	Leaf blades narrowly elliptic to lanceolate, 4–8 × 1–2 mm; seeds 1–1.3 mm; involucral gland appendages 0.1–0.2 mm, often rudimentary; s Florida.		36 Euphorbia cumulicola
+	Leaf blades oblong to oblong-elliptic or oblong-obovate, 4–15 × 2–6 mm; seeds 1.1–1.9 mm; involucral gland appendages absent or 0.1–1 mm; widespread, including s Florida		(77)
77 (76)	Leaf blades oblong or elliptic-oblong, 2–3 mm wide; involucral gland appendages (0–)0.1–0.5(–0.7) mm; styles 0.2–0.3 mm; coastal, Texas to Virginia.		29 Euphorbia bombensis
+	Leaf blades oblong, oblong-elliptic, or oblong-obovate, 2–6 mm wide; involucral gland appendages (0.1–)0.5–1 mm; styles 0.2–0.6 mm; not coastal, Texas north through c United States.		41 Euphorbia geyeri
78 (71)	Stems erect to ascending		(79)
+	Stems prostrate or reclining		(80)
79 (78)	Stems glabrous; stipules triangular; involucral gland appendages (0–)0.1–0.2 mm; seeds 0.7–1 mm; Florida.		74 Euphorbia porteriana
+	Stems usually villous, rarely glabrous; stipules filiform; involucral gland appendages 0.2–0.4 mm; seeds 1–1.4 mm; Texas.		90 Euphorbia villifera (in part)
80 (78)	Stipules filiform; leaf blade bases cordate to rounded; seeds 1.8–2.1 mm, smooth to rugose.		35 Euphorbia cordifolia
+	Stipules subulate or scalelike; leaf blade bases rounded, oblique, or cuneate; seeds 0.8–2 mm, sculpture various (if 1.5–2 mm then with 5–7 faint transverse ridges)		(81)
81 (80)	Involucres 0.4–0.6 mm.		61 Euphorbia micromera (in part)
+	Involucres 0.6–1.8 mm (usually more than 0.8 mm)		(82)
82 (81)	Seeds 1.3–2 mm		(83)
+	Seeds 0.8–1.2 mm		(84)
83 (82)	Involucral glands subcircular; involucral gland appendages present; seeds 1.3–1.5 mm; leaf blades oblong, ovate-oblong, or narrowly elliptic-oblong; vicinity of Rio Grande, w Texas.		43 Euphorbia golondrina
+	Involucral glands elliptic; involucral gland appendages absent; seeds 1.5–2 mm; leaf blades orbiculate, oval, or shortly oblong; widespread in Texas.		82 Euphorbia simulans
84 (82)	Seeds smooth or faintly rippled; involucral glands oblong, appendages 0.1–0.2 mm; leaf blade apices obtuse to acute.		72 Euphorbia polycarpa (in part)
+	Seeds with deep transverse ridges; involucral glands subcircular to slightly elliptic, appendages (0–)0.1–0.4 mm; leaf blade apices rounded, occasionally slightly emarginate.		84 Euphorbia theriaca