Petty Spurge - Euphorbia peplus
Other Names:
Cancer Weed, Radium Weed
Glabrous annual. Stems erect, 10–30 cm, branched in the inflorescence. Leaves alternate, petiolate; blades obovate with rounded tips, entire, 5–25 mm long. Inflorescence a dichotomously branched umbel with leaf-like bracts. Cyathia ca. 1 mm long, glands with attenuate-lunate appendages. Capsule ca. 2 mm long, smooth (
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).