Herbs, rarely subshrubs or shrubs, annual or perennial, with taproot or thickened rootstock. Stems usually prostrate, sometimes erect, ascending, reclining, or decumbent, branched [unbranched], terete or flattened, glabrous or hairy. Leaves opposite (rarely whorled in E. fendleri); stipules present, deciduous, (sometimes appearing absent in E. acuta), interpetiolar (at base of petiole in E. acuta); petiole present [absent], glabrous or hairy; blade monomorphic, base usually asymmetric, rarely symmetric, margins entire or variously toothed, surfaces glabrous or hairy; venation usually palmate or palmate at base and pinnate distally, sometimes pinnate, often only midvein conspicuous. Cyathial arrangement: terminal or axillary, solitary or in cymose clusters or capitate glomerules; bracts absent (except for small, bractlike leaves in capitate glomerules). Involucre ± actinomorphic, not spurred; glands (2–)4, slightly concave, flat, or slightly convex; appendages petaloid or absent. Staminate flowers (0–)1–80. Pistillate flowers: ovary glabrous or hairy; styles distinct or connate basally, unbranched or 2-fid. Seeds: caruncle absent (except for a carunclelike structure in E. carunculata).

Distribution

North America, Mexico, West Indies, Bermuda, Central America, South America, Eurasia, Africa, Atlantic Islands, Indian Ocean Islands, Pacific Islands, Australia.

Discussion

Species ca. 300 (69 in the flora).

In the key and descriptions that follow, for species with mostly prostrate stems, the side of the stem toward the ground is called the lower side and the opposite side is call the upper side.

Selected References

Herndon, A. 1993. A revision of the Chamaesyce deltoidea (Euphorbiaceae) complex of southern Florida. Rhodora 95: 38–51.

Herndon, A. 1993b. Notes on Chamaesyce (Euphorbiaceae) in Florida. Rhodora 95: 352–368.

Wheeler, L. C. 1941. Euphorbia subgenus Chamaesyce in Canada and the United States exclusive of southern Florida. Rhodora 43: 97–154, 168–205, 223–286.

Yang, Y. and P. E. Berry. 2011. Phylogenetics of the Chamaesyce clade (Euphorbia, Euphorbiaceae): Reticulate evolution and long-distance dispersal in a prominent C4 lineage. Amer. J. Bot. 98: 1486–1503.

Lower Taxa

Euphorbia abramsiana, Euphorbia acuta, Euphorbia albomarginata, Euphorbia angusta, Euphorbia arizonica, Euphorbia astyla, Euphorbia blodgettii, Euphorbia bombensis, Euphorbia capitellata, Euphorbia carunculata, Euphorbia chaetocalyx, Euphorbia cinerascens, Euphorbia conferta, Euphorbia cordifolia, Euphorbia cumulicola, Euphorbia deltoidea, Euphorbia fendleri, Euphorbia florida, Euphorbia garberi, Euphorbia geyeri, Euphorbia glyptosperma, Euphorbia golondrina, Euphorbia gracillima, Euphorbia hirta, Euphorbia hooveri, Euphorbia humistrata, Euphorbia hypericifolia, Euphorbia hyssopifolia, Euphorbia indivisa, Euphorbia jaegeri, Euphorbia jejuna, Euphorbia laredana, Euphorbia lasiocarpa, Euphorbia lata, Euphorbia maculata, Euphorbia meganaesos, Euphorbia melanadenia, Euphorbia mendezii, Euphorbia mesembrianthemifolia, Euphorbia micromera, Euphorbia missurica, Euphorbia nutans, Euphorbia ocellata, Euphorbia ophthalmica, Euphorbia parishii, Euphorbia parryi, Euphorbia pediculifera, Euphorbia perennans, Euphorbia pergamena, Euphorbia platysperma, Euphorbia polycarpa, Euphorbia polygonifolia, Euphorbia porteriana, Euphorbia prostrata, Euphorbia rayturneri, Euphorbia revoluta, Euphorbia serpens, Euphorbia serpillifolia, Euphorbia serrula, Euphorbia setiloba, Euphorbia simulans, Euphorbia stictospora, Euphorbia theriaca, Euphorbia thymifolia, Euphorbia trachysperma, Euphorbia vallis-mortae, Euphorbia velleriflora, Euphorbia vermiculata, Euphorbia villifera

Key

1	Ovaries and capsules ± hairy.	> 2
2	Cyathia in capitate glomerules (with reduced, bractlike leaves subtending cyathia).	> 3
3	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.	Euphorbia lasiocarpa
3	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	Glomerules of cyathia terminal and axillary, axillary glomerules sessile or at tips of elongated, leafless stalks.	Euphorbia hirta
4	Glomerules of cyathia terminal, on main stems or short, leafy, axillary branches, with reduced, bractlike leaves subtending cyathia.	> 5
5	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.	Euphorbia capitellata
5	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.	Euphorbia ophthalmica
2	Cyathia solitary or in small, cymose clusters at distal nodes, on congested, axillary branches, or at branch tips.	> 6
6	Involucral gland appendages unequal.	> 7
7	Seeds 3-angled to almost round in cross section, with 4–5 rounded, transverse ridges encircling seed; Arizona, California.	Euphorbia pediculifera
7	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	Styles 0.8–1.3 mm, usually unbranched, rarely 2-fid at apex; sw United States from Arizona to Texas.	Euphorbia indivisa
8	Styles 0.4–1 mm, 2-fid; Florida, Louisiana.	> 9
9	Stems pilose.	Euphorbia conferta
9	Stems strigose to sericeous or strigose-tomentulose.	> 10
10	Capsules well exserted from involucre at maturity; seeds with 3 or 4 transverse sulci alternating with low transverse ridges.	Euphorbia pergamena
10	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.	Euphorbia thymifolia
6	Involucral gland appendages ± equal in size or rudimentary to absent.	> 11
11	Leaf margins toothed, at least toward apex.	> 12
12	Styles unbranched.	> 13
13	Stems strigillose; seeds broadly ovoid, 1.2–1.4 × 1–1.1 mm, with 2 well-defined transverse ridges.	Euphorbia rayturneri
13	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).	Euphorbia stictospora
12	Styles 2-fid.	> 14
14	Capsules with pubescence concentrated along keels or toward base, often glabrous between keels.	> 15
15	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.	Euphorbia mendezii
15	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.	Euphorbia prostrata
14	Capsules ± evenly hairy or pubescence at least not concentrated only along keels and base, not glabrous between keels.	> 16
16	Capsules pilose to villous.	> 17
17	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.	Euphorbia serpillifolia
17	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.	Euphorbia velleriflora
16	Capsules strigose to sericeous.	> 18
18	Capsules scarcely exserted from involucre, base often remaining inside involucre and splitting one side of it during maturity.	Euphorbia thymifolia
18	Capsules well exserted from involucre at maturity.	> 19
19	Stems rooting at nodes; styles 0.5–0.8 mm; seeds bluntly angled, smooth or papillate.	Euphorbia humistrata
19	Stems not rooting at nodes; styles 0.3–0.4 mm; seeds sharply angled, with 3–4 low transverse ridges.	Euphorbia maculata
11	Leaf margins entire (rarely sparsely serrulate in E. garberi and E. laredana).	> 20
20	Capsules with pubescence concentrated along keels or toward base, often glabrous or less hairy between keels.	Euphorbia laredana
20	Capsules ± evenly hairy or pubescence at least not concentrated only along keels and base, not glabrous between keels.	> 21
21	Involucral gland appendages divided into 3–8 triangular to subulate segments.	> 22
22	Shrubs; stems ascending, puberulent to shortly hirsute; stipules 0.3–0.5 mm; seeds 1.4–1.5 mm.	Euphorbia jaegeri
22	Annual herbs; stems prostrate, villous, hairs glandular-glistening; stipules rudimentary to 0.2 mm; seeds 0.8–1 mm.	Euphorbia setiloba
21	Involucral gland appendages entire, toothed, or absent.	> 23
23	Proximal leaf blades ovate to ovate-elliptic, distal ones linear to elliptic-linear, more than 6 times as long as wide.	Euphorbia angusta
23	Leaf blades not linear (rarely linear in E. pediculifera), less than 3 times as long as wide.	> 24
24	Stems glabrous or sparsely hairy.	Euphorbia deltoidea
24	Stems conspicuously and densely hairy.	> 25
25	Stems with appressed hairs.	> 26
26	Leaf blade apices long-acuminate and spinulose; seeds 2.2–2.6 mm.	Euphorbia acuta
26	Leaf blade apices acute to obtuse or rounded; seeds 0.8–1.8(–2) mm.	> 27
27	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.	Euphorbia pediculifera
27	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	Involucral glands deep red, purple, or purple-black.	> 29
29	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.	Euphorbia cinerascens
29	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.	Euphorbia melanadenia
28	Involucral glands green to yellow-green or brown.	> 30
30	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.	Euphorbia lata
30	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	Stems wiry, less than 1 mm diam., 5–20 cm; leaf blades deltate, 2–5(–7) × 1–4.5 mm.	Euphorbia deltoidea
31	Stems not wiry, 1–3 mm diam., 15–50 cm; leaf blades ovate to oblong-elliptic, 4–9(–15) × 3–6 mm.	Euphorbia garberi
25	Stems with spreading to erect hairs.	> 32
32	Stems and leaves with glistening hairs; stipules (0–)0.1 mm.	Euphorbia arizonica
32	Stems and leaves without glistening hairs; stipules 0.2–1.6 mm.	> 33
33	Involucres 0.4–0.6 × 0.5–0.9 mm, glands 0.1 × 0.1–0.2 mm, appendages absent.	Euphorbia micromera
33	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	Involucral gland appendages ciliate-puberulent adaxially; perennial herbs.	Euphorbia vallis-mortae
34	Involucral gland appendages not ciliate-puberulent adaxially; annual or perennial herbs.	> 35
35	Seeds 1.1–1.7 × 0.8–1.3 mm.	Euphorbia ocellata
35	Seeds 0.8–1.2 × 0.5–0.8 mm.	> 36
36	Stems prostrate to ascending, mat-forming; sw United States.	Euphorbia polycarpa
36	Stems ascending to erect, not mat-forming; s Florida.	> 37
37	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.	Euphorbia deltoidea
37	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.	Euphorbia garberi
1	Ovaries and capsules glabrous.	> 38
38	Leaf blades linear, 5 times or more as long as wide, bases symmetric or subsymmetric (sometimes slightly asymmetric in E. parryi).	> 39
39	Leaf blade margins serrulate.	Euphorbia florida
39	Leaf blade margins entire.	> 40
40	Stipules entire; seeds 0.9–1.4 mm, 4-angled in cross section.	> 41
41	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.	Euphorbia gracillima
41	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.	Euphorbia revoluta
40	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
42	Stems erect or ascending; involucral gland appendages 0.4–2.5 × 1.1–1.7 mm.	Euphorbia missurica
42	Stems usually prostrate, rarely ascending-erect; involucral gland appendages 0.2–0.6 × 0.3–0.7(–1.1) mm.	Euphorbia parryi
38	Leaf blades not linear, 4 times or less as long as wide, bases usually asymmetric, rarely subsymmetric to symmetric.	> 43
43	Styles unbranched.	> 44
44	Annual herbs with slender taproots; leaf blade margins serrulate to denticulate; styles filiform, 1.8–2.6 mm; California.	Euphorbia hooveri
44	Perennial herbs with thickened taproots; leaf blade margins entire; styles thickened-clavate, 0.3–0.5 mm; Texas.	> 45
45	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.	Euphorbia astyla
45	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.	Euphorbia jejuna
43	Styles 2-fid at least toward apex.	> 46
46	Cyathia in capitate glomerules (with reduced, bractlike leaves subtending cyathia).	> 47
47	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.	Euphorbia capitellata
47	Stipules connate, deltate, entire; leaf blades obliquely oblong-oblanceolate, 10–35 × 7–15 mm; stems and leaves glabrous.	Euphorbia hypericifolia
46	Cyathia solitary or in small cymose clusters at distal nodes or on congested, axillary branches.	> 48
48	Leaf blade margins toothed (at least toward apex or on majority of leaves).	> 49
49	Seeds with prominent transverse ridges that interrupt abaxial keel.	> 50
50	Stems shortly pilose or puberulent proximally (often glabrous distally); capsules 1.3–1.5 × 1.1–1.5 mm.	Euphorbia abramsiana
50	Stems glabrous; capsules 1.3–1.9 × 1.6–2 mm.	Euphorbia glyptosperma
49	Seeds without prominent transverse ridges, or if present, not interrupting abaxial keel.	> 51
51	Largest leaf blades more than 20 mm.	> 52
52	Seeds 1.9–2.3 × 1.3–1.4 mm; stems and leaves glabrous.	Euphorbia trachysperma
52	Seeds 1–1.6 × 0.5–1.1 mm; stems and leaves glabrous or hairy.	> 53
53	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.	Euphorbia hyssopifolia
53	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.	Euphorbia nutans
51	Largest leaf blades less than 20 mm.	> 54
54	Leaf blade surfaces papillate; cocci of capsule often elongated and terminating in empty portion.	Euphorbia villifera
54	Leaf blade surfaces not papillate; cocci of capsule not elongated or terminating in empty portion.	> 55
55	Stem and leaves glabrous.	> 56
56	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.	Euphorbia meganaesos
56	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.	Euphorbia serpillifolia
55	Stem and leaves usually hairy, rarely glabrate.	> 57
57	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.	Euphorbia serrula
57	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	Stems prostrate to ascending, often mat-forming; cyathial glands yellow to pink; seeds smooth to dimpled or rugose, or with faint transverse ridges; California.	Euphorbia serpillifolia
58	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.	Euphorbia vermiculata
48	Leaf blade margins entire (occasionally toothed in E. blodgettii; rarely sparsely serrate in E. porteriana).	> 59
59	Stipules (at least those of upper side of stem) connate, forming deltate, ligulate, or ovate scale.	> 60
60	Subshrubs or shrubs; stems erect to ascending; leaf blade bases slightly asymmetric.	Euphorbia mesembrianthemifolia
60	Herbs; stems prostrate to decumbent and often rooting at nodes; leaf blade bases asymmetric.	> 61
61	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.	Euphorbia albomarginata
61	Annuals, rarely short-lived perennials; involucral glands 0.1 × 0.1–0.3 mm, appendages 0–0.2 × 0.1–0.3 mm; leaf blades without red blotch.	> 62
62	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.	Euphorbia blodgettii
62	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.	Euphorbia serpens
59	Stipules usually distinct, occasionally connate basally (rarely connate to middle in E. platysperma), not forming conspicuous, deltate, ligulate, or ovate scale.	> 63
63	Perennial herbs or subshrubs with thickened and often woody rootstocks.	> 64
64	Seeds 1.6–2.4 mm.	> 65
65	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.	Euphorbia perennans
65	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	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
66	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.	Euphorbia fendleri
64	Seeds 0.8–1.4 mm.	> 67
67	Stipules usually glabrous (occasionally sparsely hairy with appressed uncinate hairs in E. deltoidea).	> 68
68	Stems prostrate; stems and leaf blades glabrous or sparsely hairy with appressed uncinate hairs; s Florida.	Euphorbia deltoidea
68	Stems erect to ascending; stems and leaf blades usually villous, rarely glabrous; Texas.	Euphorbia villifera
67	Stipules pilose to hirsute.	> 69
69	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.	Euphorbia parishii
69	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.	Euphorbia polycarpa
63	Annual, rarely short-lived perennial, herbs with taproots or spreading rootstocks.	> 70
70	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.	Euphorbia carunculata
70	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	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
72	Seeds (2–)2.2–2.8 mm, weakly dorsiventrally compressed in cross section.	> 73
73	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.	Euphorbia platysperma
73	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.	Euphorbia polygonifolia
72	Seeds 0.7–2.1 mm, terete to bluntly sub- or 3-angled in cross section.	> 74
74	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.	Euphorbia missurica
74	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	Leaf blades ovate to deltate or falcate; w United States.	Euphorbia ocellata
75	Leaf blades elliptic, oblong, or lanceolate; c United States to Gulf and Atlantic coasts.	> 76
76	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.	Euphorbia cumulicola
76	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	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.	Euphorbia bombensis
77	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.	Euphorbia geyeri
71	Seeds usually 3–4-angled in cross section (± weakly angled in E. villifera), smooth to rugose or wrinkled, or with transverse ridges.	> 78
78	Stems erect to ascending.	> 79
79	Stems glabrous; stipules triangular; involucral gland appendages (0–)0.1–0.2 mm; seeds 0.7–1 mm; Florida.	Euphorbia porteriana
79	Stems usually villous, rarely glabrous; stipules filiform; involucral gland appendages 0.2–0.4 mm; seeds 1–1.4 mm; Texas.	Euphorbia villifera
78	Stems prostrate or reclining.	> 80
80	Stipules filiform; leaf blade bases cordate to rounded; seeds 1.8–2.1 mm, smooth to rugose.	Euphorbia cordifolia
80	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	Involucres 0.4–0.6 mm.	Euphorbia micromera
81	Involucres 0.6–1.8 mm (usually more than 0.8 mm).	> 82
82	Seeds 1.3–2 mm.	> 83
83	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.	Euphorbia golondrina
83	Involucral glands elliptic; involucral gland appendages absent; seeds 1.5–2 mm; leaf blades orbiculate, oval, or shortly oblong; widespread in Texas.	Euphorbia simulans
82	Seeds 0.8–1.2 mm.	> 84
84	Seeds smooth or faintly rippled; involucral glands oblong, appendages 0.1–0.2 mm; leaf blade apices obtuse to acute.	Euphorbia polycarpa
84	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.	Euphorbia theriaca