[*] Seeds smooth and even; leaves entire; whole plant glabrous.
1. E. polygonifòlia, L. Prostrate-spreading; leaves oblong-linear, obtuse, mucronate, slightly cordate or obtuse at base (4–8´´ long); stipules setaceously divided; peduncles in the forks, as long as the petioles; lobes of the involucre longer than the minute not appendaged glands; pods obtusely angled; seeds ovate (over 1´´ long, the largest of this section).—Sandy shores of the Atlantic and of the Great Lakes.
2. E. Géyeri, Engelm. Procumbent; leaves oblong-ovate, obtuse, slightly mucronate, mostly acutish at base, lowermost cordate (3–6´´ long); stipules setaceously divided; peduncles as long as the petioles, at length in loose foliaceous lateral clusters; glands with narrow white or red appendages; pods acutely angled; seeds ovate, acute at one end (½´´ long).—Sandy soil, Ill. to Wisc., Minn., and Kan.
3. E. petaloìdea, Engelm. Resembling the last, but half-erect and spreading; leaves longer, narrower, retuse or emarginate; peduncles longer than the petioles; involucres larger, the broadly campanulate appendages much larger and conspicuous; pod obtusely angled; seeds nearly 1´´ long.—From Iowa and Mo., westward.
4. E. sérpens, HBK. Stems filiform, prostrate, and often rooting; leaves round-ovate, obtuse or cordate at base (only ½–1½´´ long); stipules membranaceous, triangular; peduncles much longer than the petioles, at length in loose foliaceous lateral clusters; glands of the very small involucre with minute crenulate appendages; pods acutely angled; seeds obtusely angled (½´´ long or less).—Rich soil, Ill. and Iowa to Kan., and southward. Rarely adv. eastward.
[*][*] Seeds minutely roughened or transversely wrinkled or pitted; leaves more or less serrulate, smooth or often hairy.
5. E. serpyllifòlia, Pers. Glabrous, prostrate-spreading; leaves obovate-oblong, narrowed at the very oblique base, sharply serrulate toward the obtuse apex (3–6´´ long, often with a red spot); stipules lanceolate, fimbriate; peduncles as long as or longer than the petioles, at length in loose foliaceous lateral clusters; glands of the small involucre with narrow somewhat toothed appendages; pods sharply angled; seeds acutely quadrangular, slightly cross-wrinkled, often pitted (nearly ¾´´ long).—Wisc. to Mo., and westward.
6. E. glyptospérma, Engelm. Glabrous (or very rarely puberulent), erect-spreading; leaves linear-oblong, mostly falcate, very unequal at base, slightly serrulate toward the obtuse apex (2–5´´ long); stipules lanceolate, setaceously divided; peduncles as long as the petioles, in dense foliaceous lateral clusters; glands of the very small involucre with narrow crenulate appendages; pods sharply angled; seeds sharply 4-angled and with 5 or 6 sharp transverse wrinkles (½´´ long).—Ont. to Wisc., Ill., Mo., and westward.
7. E. maculàta, L. Prostrate; stems puberulent or hairy; leaves oblong-linear, very oblique at base, serrulate upward, more or less pubescent or sometimes smoothish (4–6´´ long), usually with a brown-red spot in the centre; stipules lanceolate, fimbriate; peduncles as long as the petioles, in dense foliaceous lateral clusters; glands of the small involucre minute, with narrow slightly crenate (usually red) appendages; pods acutely angled, puberulent; seeds ovate ({2/5}´´ long), sharply 4-angled and with about 4 shallow grooves across the concave sides.—Open places, roadsides, etc., common.
8. E. humistràta, Engelm. Procumbent, puberulent or hairy; leaves elliptical or obovate, very oblique at base, serrulate toward the apex, sparsely hairy underneath (4–9´´ long, sometimes with a brown spot above); stipules lanceolate, fimbriate; peduncles rather shorter than the petioles, in dense scarcely foliaceous lateral clusters; involucre cleft on the back, its (red or white) appendages truncate or crenate; pods sharply angled, puberulent; seeds ovate, obtusely angled, minutely roughened (½´´ long).—Rich soil, Ind. and W. Tenn. to Minn. and Kan.