[+] Seeds and ovules 2 in each cell; flowers moncious.

2. Pachysandra. Flowers in basal spikes. Calyx 4-parted. Stamens 4, distinct.

3. Phyllanthus. Flowers axillary. Stamens 3, united.

[+][+] Seeds and ovules 1 in each cell.

[a.] Flowers apetalous, in cymose panicles (2--3-chotomous); stamens 10, erect in the bud.

4. Jatropha. Calyx corolla-like, the staminate salver-form; armed with stinging hairs.

[b.] Flowers in terminal racemes or spikes. Stamens inflexed in the bud.

Stellate-downy or scurfy, or hairy and glandular; leaves mostly entire.

5. Croton. Flowers spiked or glomerate. Ovary and fruit 3- (rarely 2--4-) celled.

6. Crotonopsis. Flowers scattered on the branchlets. Ovary and fruit 1-celled.

[c.] Flowers in axillary spikes or racemes (except n. 9), apetalous (except n. 7). Stamens 8 or more; anthers erect in the bud.

7. Argythamnia. Petals and sepals 5. Stamens 10--15, united. Styles bifid, linear.

8. Acalypha. Calyx 4- (3--5-) parted. Stamens mostly 8. Fertile flowers in the axils of leafy bracts. Stigmas finely dissected.

9. Ricinus. Racemes terminal, subpanicled. Calyx 3--5-parted. Stamens very numerous; the filaments repeatedly branched. Styles 2-parted.

[d.] Flowers apetalous, in racemes or spikes pistillate at base. Stamens 2 or 3. Styles simple.

10. Tragia. Flowers racemose. Calyx-lobes valvate in bud. Hirsute or p.u.b.escent.

11. Stillingia. Flowers spicate. Calyx-lobes imbricate in bud. Fertile bracts glanduliferous. Glabrous.

1. EUPHoRBIA, L. SPURGE.

Flowers moncious, included in a cup-shaped 4--5-lobed involucre (_flower_ of older authors) resembling a calyx or corolla, and usually bearing large thick glands (with or without petal-like margins) at its sinuses. Sterile flowers numerous and lining the base of the involucre, each from the axil of a little bract, and consisting merely of a single stamen jointed on a pedicel like the filament; anther-cells globular, separate. Fertile flower solitary in the middle of the involucre, soon protruded on a long pedicel, consisting of a 3-lobed and 3-celled ovary with no calyx, or a mere vestige. Styles 3, each 2-cleft; the stigmas therefore 6. Pod separating into 3 1-seeded carpels, which split elastically into 2 valves. Seed often caruncled (ours only in ---- 5 and 6).--Plants (herbs in the United States), with a milky acrid juice.

Peduncles terminal, often umbellate-cl.u.s.tered; in the first section mostly appearing lateral, but not really axillary. (Named after _Euphorbus_, physician to King Juba.)

[A.] _Glands of the involucre with petal-like, usually white or rose-colored, margins or appendages; these almost obsolete in n. 1._

-- 1. ANISOPHLLUM. _Leaves all opposite, short-petioled, small, oblique at base; stipules awl-shaped or scaly and often fringed, persistent; stems much branched, spreading or usually proc.u.mbent; involucres solitary in the forks or in terminal or pseudo-lateral cl.u.s.ters, small, with 4 glands; seeds ash-colored (except in n. 10); annuals._

[*] _Seeds smooth and even; leaves entire; whole plant glabrous._

1. E. polygoniflia, 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 sh.o.r.es of the Atlantic and of the Great Lakes.

2. E. Geyeri, Engelm. Proc.u.mbent; _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 cl.u.s.ters; glands with _narrow white or red appendages_; pods acutely angled; seeds ovate, acute at one end (" long).--Sandy soil, Ill. to Wisc., Minn., and Kan.

3. E. petalodea, 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. serpens, HBK. Stems filiform, prostrate, and often rooting; _leaves round-ovate_, obtuse or cordate at base (only --1" long); _stipules membranaceous, triangular_; peduncles much longer than the petioles, at length in loose foliaceous lateral cl.u.s.ters; glands of the very small involucre with _minute crenulate appendages_; pods acutely angled; seeds obtusely angled (" 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. serpylliflia, 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 cl.u.s.ters; glands of the small involucre with narrow somewhat toothed appendages; pods sharply angled; _seeds acutely quadrangular, slightly cross-wrinkled_, often pitted (nearly " long).--Wisc. to Mo., and westward.

6. E. glyptosperma, Engelm. Glabrous (or very rarely p.u.b.erulent), 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 cl.u.s.ters; 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_ (" long).--Ont. to Wisc., Ill., Mo., and westward.

7. E. maculata, L. Prostrate; stems p.u.b.erulent or hairy; _leaves oblong-linear_, very oblique at base, serrulate upward, more or less p.u.b.escent 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 cl.u.s.ters; glands of the small involucre minute, with narrow slightly crenate (usually red) appendages; pods acutely angled, p.u.b.erulent; _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. humistrata, Engelm. Proc.u.mbent, p.u.b.erulent or hairy; _leaves elliptical or obovate_, very oblique at base, serrulate toward the apex, spa.r.s.ely 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 cl.u.s.ters; _involucre cleft on the back_, its (red or white) appendages truncate or crenate; pods sharply angled, p.u.b.erulent; _seeds ovate, obtusely angled, minutely roughened_ (" long).--Rich soil, Ind. and W. Tenn. to Minn. and Kan.

9. E. Preslii, Guss. Smooth or with scattered hairs, ascending or erect (1--2 high); leaves oblique at the obtuse or slightly cordate base, ovate-oblong or oblong-linear, sometimes falcate, serrate (--1' long), often with a red spot or red margins; stipules triangular; peduncles longer than the petioles, collected in loose leafy terminal cymes; _appendages entire_, larger and white, or smaller and sometimes red; _pod glabrous, obtusely angled; seeds ovate, obtusely angled, wrinkled and tubercled_ (" long), blackish. (E. hypericifolia of _Man._, not _L._)--Common throughout the U. S. east of the plains.

-- 2. ZYGOPHYLLiDIUM. _Leaves opposite, on short petioles, not oblique, with stipular glands; stems dichotomously branched, erect; cymes terminal; involucres with 5 glands; seeds tuberculate._

10. E. hexagona, Nutt. Somewhat hairy (1 high or more); branches striate-angled; leaves linear-lanceolate, entire; involucre hairy without and within; glands with green ovate-triangular appendages twice their length; capsule smooth; seeds ovate.--Iowa to Tex., west to Col.

and Montana.

-- 3. PETALMA. _Uppermost leaves with conspicuous white petal-like margins, whorled or opposite, the others scattered; erect annuals, with leaves equal at base and entire, and with lanceolate deciduous stipules; involucres 5-lobed, in an umbel-like inflorescence._

11. E. marginata, Pursh. Stem stout (2--3 high), erect, hairy; leaves sessile, ovate or oblong, acute; umbel with 3 dichotomous rays; glands of the involucre with broad white appendages.--Minn. to Mo., west to Col., also spreading eastward to Ohio, and frequently escaped from gardens, where it is often cultivated for its showy broadly white-margined floral leaves.

-- 4. t.i.tHYMALoPSIS. _Only the uppermost leaves whorled or opposite; erect perennials, with entire leaves equal at base; stipules none; involucres mostly 5-lobed, in the forks of the branches and terminal; inflorescence umbelliform._

12. E. corollata, L. Glabrous or sometimes sparingly hairy (2--3 high); leaves ovate, lanceolate, or linear, entire, obtuse; umbel 5- (3--7-) forked, and the forks again 2--3- (or rarely 5-) forked; involucres long-peduncled, with showy white appendages (appearing like petals), the lobes minute and incurved; pod slender-pedicelled, smooth; seeds thick (1" long or more), ash-colored, slightly uneven.--Rich or sandy soil, N. Y. and N. J. to Fla., west to Minn. and La., also adventive in Ma.s.s.

July--Oct.

[B.] _Glands of the involucre without petaloid appendages._

-- 5. POINSeTTIA. _Involucres in terminal cl.u.s.ters, 4--5-lobed, with few (or often solitary) cup-shaped glands; erect annuals, with variable, entire, dentate, or sinuate leaves, all or only the upper ones opposite; the uppermost often colored, especially at base; stipules small and glandular._

13. E. dentata, Michx. Erect or ascending, hairy (1 high); leaves ovate, lanceolate, or linear, petioled, coa.r.s.ely toothed (1--2' long), _only the lowest alternate_, the upper often paler at base; involucres almost sessile, with 5 oblong dentate lobes, and one or sometimes more _short-stalked glands_; seeds ovate-globular, slightly tubercled.--Rich soil, Penn. to Tenn., Iowa, E. Kan., and southward. July--Sept.

14. E. heterophlla, L. Erect (1--3 high), glabrous; _leaves alternate_, petioled, ovate-fiddle-shaped and sinuate-toothed, or lanceolate or linear and entire, often only those of the branches linear; the upper usually with a red base; involucres about the length of the peduncle, with 5 ovate incised lobes and a single or few and _almost sessile glands_; seeds nearly globular, tubercled.--Slopes and rocky soil, Minn. to W. Ill., Iowa and Mo.

-- 6. t.i.tHMALUS. _Involucres in a terminal dichotomous or commonly umbelliform inflorescence, 5- or usually 4-lobed, with as many flat or convex entire or crescent-shaped glands; seeds carunculate (except n. 15); ours ascending or erect, and mostly glabrous, without stipules._

[*] _Perennials with entire leaves, all or only the upper opposite; involucres long-peduncled in a dichotomous inflorescence, mostly with 5 transversely oblong glands; seeds without caruncle._

15. E. Ipecacuanhae, L. Stems many from a very long perpendicular root, erect or diffusely spreading (5--10' long), forking from near the base; leaves varying from obovate or oblong to narrowly linear, almost sessile, glabrous; peduncles elongated (--1' long); pod long-pedicelled, obtusely angled, nearly smooth; seed ovate, white, spa.r.s.ely marked with impressed dots.--Sandy soil, near the coast; Conn.

to Fla.; also barrens of S. Ind.

[*][*] _Leaves scattered, only the floral in the umbelliform inflorescence whorled or opposite and of a different shape; glands mostly 4._

[+] _Leaves serrulate or rarely entire; glands transversely oval, obtuse._

[++] _Seeds smooth and even; pod warty or rough._