Spurges (Euphorbia)

..... many or all of the lvs alternate except in #6 & #14   strictly opposite lvs  
..... stem terminated by a proliferating umbel of 3-many rays subtended by a whorl of lvs not terminated by umbel subtended by a whorl of lvs lvs opposite or much more often alternate or partly whorled lvs all opposite
1) glands of the involucre without petaloid appendages ..... ..... ..... .....
glands of the involucre regularly 4, oval to crescent-shaped, never bilabiate Group I ..... ..... .....
glands usually 1, rarely more, tangentially bilabiate ..... Group II ..... .....
1) glands of the involucre w/ small or conspicuous, white or rarely colored, petaloid appendages (or the appendages scarcely developed in some spp.) ..... ..... ..... .....
glands & petaloid appendages 5 ..... ..... Group III .....
glands and petaloid appendages 4 ..... ..... ..... Group IV

involucre = set of bracts beneath the inflorescence

Group I

..... cauline lvs: alt alt opposite
  alt, 5-10cm 1-5 lvs  
1) gland of the involucres transverely oval or elliptic or subrotund ..... ..... .....
seeds smooth or very obscurely reticulate; perennial purple spurge (1.purpurea = purple) dry or moist woods, rare ..... flat-lvd spurge (3.platyphyllos) European in waste places
seeds distinctly areolate; annual wartweed spurge (4.helioscopia) green fls; Eurp intro ..... .....
1) glands of the involucre reniform or crescent-shaped with the concave side outward ..... ..... .....
seeds 4-6mm ..... ..... myrtle spurge (6.lathyrus = the classical name) escape
seeds 1-3mm ..... ..... .....
7)rays of the umbel mostly 3-5 ..... ..... .....
seeds pitted ..... ..... petty spurge (9.peplus) Eurasian intro
seeds tuberculate ..... (10. exigua) introduced; e Canada to WV .....
7) rays of the umbel us. more than 5 ..... ..... .....
pr. cauline lvs 1-2cm wide, distinctly pinnately veined ..... shining spurge (11.lucida) European, rare weed .....
pr. cauline lvs less than 1cm wide; yellow flowers ..... cypress spurge (13.cyparissias = cypress-like) lvs 1-3cm x 1-3mm; 1.5-3dm high; roadsides, waste ground; ME to VA

leafy spurge (12.esula) lvs 3-8cm x 4-8mm; 3-7dm high; Eurasian widely estab; N. Eng. to MD

 .....

Group II

..... principal cauline lvs all or mostly: alternate opposite
herbage glabrous or nearly so fire-on-the mountain (15.cyathophora = cup-bearing) X; n to VA .....
more or less pubescent ..... toothed spurge (14.dentata0 dry soil; roadsides & waste places; IL to Mexico & eastward

Group III

..... alt/whorled lvs:   opposite:
..... lvs obtuse to retuse; stems branched from middle or above lvs terminating in a sharp point stems branched from base
appendages white, conspicuous ..... snow-on-the mountain (2.marginata = margined, upper lvs) white margins on leafy bracts; prairies & plains; MN to MO .....
appendages white (rarely green) consp. much exceeding the gland and commonly as long as or longer than wide flowering spurge (16.corollata) dry woods & old fields: MA to FL ..... ......
appendages very short or apparely none, no longer (radially) than the gland; appendages green ..... ..... ipecac spurge (18.ipecacuanhae) in sand, chiefly on coastal plain: LI to GA

Group IV

..... young stem & lvs glabrous   young stems pubescent:
..... lvs entire lvs serrulate .....
3)stipules separate seaside spurge (22.polygonifolia) not hairy; red-stemmed crawler; sand dunes & beaches; QE to GA ..... .....
3)stipules united into a triangular, scale-like, often lobed or frined structure round-leaved spurge (26.serpens) moist alluvial soil; s ON to TN & FL ..... .....
7) seeds smooth to obscurely rougheened or pitted, not transversely ridged ..... thyme-leaved spurge (27.serpyllifolia) occ introduced .....
7) seeds w/ 3 or 4 evident transverse ridges ..... ridge-seed spurge (28.glyptosperma) dry sandy soil; QE to NY .....
ovary and capsule glabrous ..... ..... eyebane spurge (29.nutans) stems ascending or suberect; dry or moist soil, abundant in lawns & gardens; NH to FL

(30.vermiculata) stems prostrate or widely spreading; fields, roadsides, waste grounds; NS to NJ
ovary and capsule pubescent ..... ...... milk-purslane spurge (31.maculata) involucre cleft on one side a fourth to a third its length; matted, prostrate; purple-blotched lvs; hairy; very abudnant as a weed in lawns, gardens & wate places, also in meadows & open woods

(32.humistrata) involucre cleft on one side fully half its length; moist alluvial soil; OH to AL & TX