642 



EUPHORBIACEAE 



Euphorbia 



50 



Map 1328 



Euphorbia marginata Pursh 



U 



Miles 



50 



Map 1329 



Euphorbia polygonifolia L 



50 



Map 1330 



Euphorbia serpens H BK 



Leaves mostly elliptic, mostly 7x12 mm to 8x16 mm, usually glabrous be- 

 neath, generally serrate only above the middle or at the apex; capsules 

 usually not exserted beyond the involucre, the lobes mostly acute; seed 

 1 mm long, usually no transverse lines plainly visible after the seed 



is cleaned, the surface minutely roughened ">. E. humistrata. 



Leaves alternate or scattered on the stem, not oblique at the base. .9. E. corolla tct. 

 Glands of the involucre naked (with no petallike appendage). 

 Leaves opposite. 



Leaves oblique at the base; annual, glabrous 2. E. polygonifolia. 



Leaves not oblique at the base ; plants glabrous or pubescent. 



Perennial plants with several stems from a stout rootstock, glabrous; 



flowering in the spring. (See excluded species no. 421, p. 1070) 



E. Ipecacuanhae. 



Annual plants; flowering in summer; stem more or less densely retrorsely 

 puberulent in addition to long colorless multicellular hairs; leaves more or 

 less densely short- or long-pubescent both above and beneath ; glands of in- 

 volucre stipitate 10. E. dentata. 



Leaves all alternate or scattered. 



Stems not topped by an umbel; stems and leaves glabrous or nearly so; glands of 



involucre sessile 11. E. heterophylla. 



Stems topped by a several-rayed umbel. 



Leaves serrulate 12. E. obtusata. 



Leaves entire. 



Plants perennial; seeds smooth. 



Stem leaves 4-12 mm wide 13. E. Evx a. 



Stem leaves 1-3 mm wide 14. E. Cyparissias. 



Plants annual or biennial; seeds pitted. 



Lobes of the capsules 2-crested 15. E. Peplii*. 



Lobes of the capsules rounded 16. E. commutata. 



1. Euphorbia marginata Pursh. (Dichrophylhtm marginatum 

 (Pursh) Kl. & Garcke.) Snow-on-the-mountain. Map 1328. Escaped 

 from cultivation in most parts of the state but not abundantly so. 



Minn, to Colo., southw. to Tex. 



