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Key to Euphorbia, Key A: subgenus Chamaesyce, section Anisophyllum, subsection Hypericifoliae {add to Key A: E. blodgettii, E. hypericifolia, E. mesembrianthemifolia, E. ophthalmica, E. serpyllifolia var. serpyllifolia}

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1 Leaves serrulate, at least at the apex (use 10× magnification); seeds with 2-4 transverse ridges WHICH TAXA BELOW 1A have smooth seeds?
  2 Leaves and stems glabrous.
    3 Seeds with 3-4 (-6) prominent transverse ridges that interrupt abaxial keel; cyathia glands red to purple (sometimes yellow on older cyathia); stems prostrate; [s. IN and c. TN westward, primarily w. of MS river]
    3 Seeds with faint ridges, not interrupting abaxial keel; cyathia glands green, brown, or yellow to pink (lacking a darkened red or purple coloration).
      4 Stems erect to ascending (the tips not drooping)
      4 Stems prostrate to ascending, drooping at tips or plants mat-forming.
        5 Staminate flowers 2-5; seeds 0.9-1.0 mm long, minutely beaded with 3-4 transerve ridges that do not interrupt abaxial keel; [coastal LA and TX only]
        5 Staminate flowers 5-20; seeds 1.0-1.4 mm long, smooth, dimpled, or rugose; [scattered in our area, widespread in w. US]
  2 Leaves and stems variously pubescent.
          6 Ovaries and capsules glabrous.
             7 Stipules connate on both sides of stems.
               8 Stipules irregularly lacerate, ca. 0.5 mm long (sometimes to 1.0 mm); stems erect to ascending, the hairs (at least sparsely) pilose proximally and glabrous distally; seeds with 2-3 prominent transverse ridges, sometimes reticulate-pitted; [native SC s. to FL, w. through TX; waif northwards]
               8 Stipules triangular, or laciniate-subulate into filiform segments; stems prostrate or erect to ascending, the hairs usually spreading hirsute, strigillose or pilose (not just proximally); seeds rugulose, sometimes also bearing low transverse ridges; [VA w. to IL northward]
             7 Stipules distinct (or only basally connate on one side of the stem in E. nutans).
                 9 Leaf blade surfaces papillate, often also with at least some long thin hairs; cocci of capsule often elongated, distally empty; [TX]
                 9 Leaf blade surfaces not papillate, pilose, villous, sericeous, or glabrous; cocci of capsule not elongated nor distally empty; [collectively widespread].
                   10 Stipules usually distinct, sometimes connate on one side of stem; capsules 1.9-2.3 mm long; stems ascending or suberect, puberulent when young; adaxial surface of leaf blade often red-mottled; [widespread throughout our area]
                   10 Stipules distinct or connate (if connate, on both sides of stem); capsules 1.4-1.8 mm long; stems prostrate or widely spreading, spreading-hirsute [VA w. to IL northward]
          6 Ovaries and capsules variously pubescent.
                     11 Stipules connate (sometimes only on one side of the stem).
                       12 Stems erect to ascending.
                          13 Stipules usually distinct, rarely connate at base, if divided the segments deltate to linear-subulate; capsules and ovaries with whitish hairs; staminate flowers 2-8; seeds 0.7-0.9 mm long, usually rugulose or with 3-6 low transverse ridges; [widespread]
                          13 Stipules distinct when young, connate into a deltate scale when older, erose or laciniate with dark glands at the base or along the margins; capsules and ovaries with yellowish hairs; staminate flowers 15-25; seeds 1.2-1.3 mm long, with 3-5 shallow depressions separated by low, inconspicuous ridges; [c. and s. FL only]
                       12 Stems prostrate.
                            14 Capsules with conspicuous glabrous areas between pubescent keels.
                              15 Seeds smooth or with faint transverse ridges, reddish-brown, orange, or grayish-pink colored; plant pubescence variously sericeous, pilose, or villous; staminate flowers 6-15; [s. FL only]
                              15 Seeds with sharp transverse ridges, white with concealed brown color beneath the seed surface; plant pubescence crisped-villous; staminate flowers 3-6; [widespread, including s. FL]
                            14 Capsules uniformly pubescent, not with conspicuous glabrous areas between keels.
                                16 Styles unbranched
                                16 Styles 2-fid.
                                  17 Capsules strigose to sericeous; involucral gland appendages unequal; staminate flowers 3-5; [LA and FL]
                                  17 Capsules pilose to villous; involucral gland appendages ± equal in size (or absent); staminate flowers 8-12; [s. TX]
                     11 Stipules distinct.
                                    18 Styles unbranched
                                    18 Styles 2-fid.
                                       19 Capsules usually glabrous between pubescent keels (the pubescence most conspicuous only on the keels).
                                         20 Seeds smooth or with faint transverse ridges, reddish-brown, orange, or grayish-pink colored; plant pubescence variously sericeous, pilose, or villous; staminate flowers 6-15; [s. FL only]
                                         20 Seeds with sharp transverse ridges, white with concealed brown color beneath the seed surface; plant pubescence crisped-villous; staminate flowers 3-6; [widespread, including s. FL]
                                       19 Capsules uniformly pubescent, not with conspicuous glabrous areas between keels.
                                           21 Cyathia clustered, or in dichotomously branched axillary inflorescences. [THIS CHARACTER NEEDS VALIDATION OR RE-WORDING, TEST IN HERBARIUM]
                                             22 Gland appendages absent
                                             22 Gland appendages present (the petaloid portion of the cyathia, distal to the glands).
                                               23 Plants with coarse pubescence, the stem trichomes consisting of larger yellow and smaller white types; stipules usually distinct, rarely connate at base (if divided the segments deltate to linear-subulate); gland appendages sometimes absent or diminuitive; staminate flowers 2-8; seeds 0.7-0.9 mm long, usually rugulose or with 3-6 low transverse ridges; [widespread]
                                               23 Plants with fine pubescence, the stem trichomes only of one white type; stipules distinct when young, connate into a deltate scale when older, erose or laciniate with dark glands at the base or along the margins; gland appendages present; staminate flowers 15-25; seeds 1.2-1.3 mm long, with 3-5 shallow depressions separated by low, inconspicuous ridges; [c. and s. FL only]
                                           21 Cyathia solitary in the leaf axils, or in reduced unbranched axillary inflorescences. [THIS CHARACTER NEEDS VALIDATION OR RE-WORDING, TEST IN HERBARIUM]
                                                 24 Gland appendages (the petaloid portion of the cyathia) conspicuously unequal in length, at least one or two shorter than the remaining appendages; plants mat-forming (E. thymifolia) or not (only occasionally in E. pergamena); [FL].
                                                    25 Plants mat-forming, stems prostate only; glands elliptic; ovary densely strigose; staminate flowers 3-5; [disturbed uplands]
                                                    25 Plants not mat-forming (only occasionally in E. pergamena), stems prostate to ascending; glands lunate (crescent-shaped) or reniform (kidney-shaped); ovary puberulent, sericeous, or pilose; staminate flowers 5-15; [intact sites, occasionally disturbed].
                                                      26 Plants annual with taproots, the stems 10-45 cm long, pilose; leaves sometimes revolute; capsules pilose; seeds orange-brown, glaucous; staminate flowers 5-8; [pine rocklands, marl prairies, or disturbed uplands]
                                                      26 Plants perennial with thickened rootstocks, the stems 5-18 cm long, sericeous on upper surface and glabrous on lower surface; leaves not revolute; capsules puberulent, sericeous, or strigillose; seeds whitish to gray; staminate flowers 15; [pine rocklands]
                                                 24 Gland appendages ± equal in length; plants usually mat-forming; [collectively widespread, including FL].
                                                        27 Plants perennial with strongly thickened and lignified roostocks; staminate flowers 8-12; [s. TX only]
                                                        27 Plants annual with taproots (or sometimes taprooted perennials in E. thymifolia); staminate flowers 2-5; [collectively widespread in our area].
                                                          28 Middle nodes of stems forming adventitious roots (slowly pull up some of the stems to see if rooted in soil)
                                                          28 Stems not forming adventitious roots (stems merely lying flat).
                                                            29 Leaves serrulate (on the longer leaf margin) or subentire; seeds 1.0-1.2 mm long; styles clavate; [widespread]
                                                            29 Leaves (the larger ones at least) usually conspicuously serrate, smaller leaves serrulate; seeds 0.7-0.9 mm long; styles slender; [FL]
1 Leaves absolutely entire; seeds smooth, variously rugose or wrinkled, or bearing 2-4+ distinct transverse ridges.
                                                              30 Stems and leaves variously pubescent, at least on the upper stem surface (except E. deltoidea ssp. deltoidea, which can be pubescent to glabrous on both sides).
                                                                 31 Capsules with glabrous areas between the pubescent keels; plants annual; [s. TX]
                                                                 31 Capsules uniformly pubescent throughout (sparsely pubescent to glabrous in E. deltoidea ssp. deltoidea, but lacking the conspicuous contrast between keels and inter-keel space described above); plants perennial; [widespread, including TX].
                                                                   32 Distal leaves linear to elliptic-linear; [TX]
                                                                   32 Distal leaves not consistently and conspicuously linear (instead elliptic to ovate); [widespread, including TX]
                                                                     33 Stems erect to ascending.
                                                                       34 Stipules filiform; [OK and TX westward]
                                                                       34 Stipules triangular or subulate; [s. FL].
                                                                         35 Gland appendages unequal in length; stem pubescence limited to the upper surface (lower stem surface glabrous)
                                                                         35 Gland appendages ± equal in length; stem pubescence on both upper and lower stem surfaces.
                                                                           36 Stipules pilose; stems not wiry, 1-3 mm in diameter
                                                                           36 Stipules villous-hirsute; stems wiry, < 1 mm in diameter.
                                                                              37 Stem and capsule pubescence villous with uncinate or irregularly twisted hairs, 0.2-0.5 mm long
                                                                              37 Stem and capsule pubescence villous-hirsute with straight, spreading hairs, 0.6-0.7 mm long
                                                                     33 Stems prostrate or decumbent.
                                                                                38 Stipules filiform; [OK and TX westward]
                                                                                38 Stipules triangular or subulate; [s. FL or s. TX].
                                                                                  39 Capsules canescent; glands purple-black; the appendages absent or forming narrow rim around distal margin of gland; [s. TX]
                                                                                  39 Capsules glabrous or variously pubescent (canescent in E. deltoidea ssp. serpyllum); glands green to yellow-green or pinkish colored; the appendages either absent, forming a narrow ring, or present; [s. FL]
                                                                                    40 Gland appendages unequal in length; glands pinkish
                                                                                    40 Gland appendages ± equal in length; glands green to yellow-green.
                                                                                      41 Leaves and stems glabrous or sparsely pubescent
                                                                                      41 Leaves and stems canescent or villous.
                                                                                        42 Stem and capsule pubescence villous with uncinate or irregularly twisted hairs, 0.2-0.5 mm long
                                                                                        42 Stem and capsule pubescence canescent with appressed hairs, < 0.1 mm long
                                                              30 Stems and leaves glabrous (on both sides).
                                                                                           43 Stipules connate, forming a conspicuous scale-like structure; stems frequently rooting at the nodes.
                                                                                             44 Leaf margins whitish; plants perennial, with a moderately to strongly thickened rootstock; [TX westward]
                                                                                             44 Leaf margins green; plants annual, or sometimes perennial with a slightly thickened rootstock (E. blodgettii); [widespread, including TX].
                                                                                               45 Glands red, the appendages unequal in length; cyathia solitary, in cymose clusters distally on stem, or in congested axillary branches; [peninsular FL]
                                                                                               45 Glands yellow, the appendages uniformly equal in length; [widespread]
                                                                                           43 Stipules distinct, not merging to form a singular scale-like structure; stems rooting or not.
                                                                                                 46 Seeds 1.6-2.4 mm long; [OK and TX westward]
                                                                                                 46 Seeds 0.8-1.4 mm long; [collectively widespread].
                                                                                                   47 Cyathia solitary at distal nodes, the distal nodes not also bearing small cymose clusters.
                                                                                                     48 Stems prostrate, plants herbaceous, sometimes mat-forming.
                                                                                                        49 Leaf blades oblong to oblong-elliptic, 2.6-7.6 mm wide; involucral glands yellowish-pink, 0.3-0.5 mm long, the gland appendages 1.1-1.5 mm long; seeds 1.8-2.1 mm long
                                                                                                        49 Leaf blades narrowly elliptic to lanceolate, 1-2 mm wide; involucral glands slightly stipitate, ca. 0.1 mm long (rudimentary), the gland appendages 0.1-0.2 mm long; seeds 1.0-1.3 mm long
                                                                                                     48 Stems erect to ascending, plants herbaceous or subshrubs, not mat-forming.
                                                                                                          50 Plants subshrubs or small shrubs, conspicuously woody; [coastal habitats, FL]
                                                                                                          50 Plants herbaceous, sometimes slightly woody at base or with a thickened root stock but plants not obviously subshrubs or shrubs; [s. TX or s. FL]
                                                                                                            51 Leaf blade surfaces papillate, often also with at least some long thin hairs; cocci of capsule often elongated, distally empty; [s. TX]
                                                                                                            51 Leaf blade surfaces not papillate, usually glabrous or nearly so; cocci of capsule not elongated or distally empty; [s. FL].
                                                                                                              52 Leaves (2.2-) 3.0-6.0 (-8.3)× longer than wide, narrowly lanceolate to linear elliptic, 1-veined; [s. FL mainland only]
                                                                                                              52 Leaves 0.01–3.0 (-3.5)× longer than wide, ovate to lanceolate, 1–3-veined; [s. FL mainland or FL keys]
                                                                                                                53 Leaf apex obtuse to rounded; cyathia gland and appendage length 0.6-1.0 mm total; [s. FL mainland only]
                                                                                                   47 Cyathia solitary, or often in small cymose clusters at distal nodes.
                                                                                                                  54 Mature seeds bluntly 3-4 angled in cross-section, 0.9-1.4 (-1.7) mm long (except E. missurica, with seeds 1.5-2.0 mm long, but with leaves conspicuously linear); leaves fleshy or not.
                                                                                                                     55 Leaves linear (at least distally); seeds 1.5-2.0 mm long
                                                                                                                     55 Leaves oblong, ovate or elliptic; seeds 0.9-1.4 (-1.7) mm long.
                                                                                                                       56 Seeds gray to reddish brown, 0.9-1.1 mm long; leaf bases asymmetric but lacking expanded round auricle; [FL]
                                                                                                                       56 Seeds ashy white with a brown longitudinal line on adaxial surface, 1.1-1.4 (-1.7) mm long; leaf bases angled or rounded, with one side of the leaf base often expanded into a small rounded auricle; [s. IL to TX, westward]
                                                                                                                  54 Mature seeds rounded in cross section, (1.3-) 1.5-2.6 mm long; leaves often somewhat fleshy; [coastal only, barrier island dunes and other sandy coastal habitats].
                                                                                                                         57 Mature seeds (1.3-) 1.5-1.9 mm long; styles 0.2–0.3 mm; [preferring habitat behind foredunes, VA s. to FL, w. to TX]
                                                                                                                         57 Mature seeds (2.0-) 2.2-2.6 mm long; styles 0.7–1 mm; [preferring pioneer habitat in front of foredunes and along upper beach areas, FL Atlantic n. to Long Island in our area]