This euphorbia is a South African native, not found in the wild in North America.
Identification: Plants are up to 12" (30 cm) in height, with blue-green stems that are roughly square in cross-section and about ⅜" (1 cm) on a side. Spine groups appear along the edges of the stems; spines are dark orange-brown and about ⅜" (1 cm) in length. Flowers are small bright yellow cyathia, appearing near the stem tips.
Euphorbia aeruginosa on CactiGuide.com
Euphorbia aeruginosa on Cal Lamke's Cal's Plant of the Week, at the University of Oklahoma's Department of Botany and Microbiology
Euphorbia aeruginosa on Desert-tropicals.com
Euphorbia aeruginosa at the University of Connecticut Ecology and Evolutionary Biology Plant Growth Facilities
Euphorbia aeruginosa on saylorplants.com
Euphorbia aeruginosa description by Thomas H. Kent, last updated 16 Aug 2013.
Range: Zones 10-11: