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Scientific: Euphorbia rigida (formerly known as Euphorbia biglandulosa)
Common: silver spurge, rigid spurge, upright myrtle spurge, gopher plant, milkweed
Family: Euphorbiaceae
Origin: Across entire Mediterranean region from Portugal across north Africa into Syria, Turkey and Iran on dry rocky slopes above 3,000 feet.

Pronounciation: U-FOR-bee-a RI-gi-da

Hardiness zones
USDA 8-11

Landscape Use: Great landscape filler for xeric landscapes, rock gardens, containers.

Form & Character: Stiff, tough, yet delicate, rounded, symmetrical, recessive, semi arid.

Growth Habit: Evergreen, herbaceous perennial subshrub, sometimes treated as a summer annual in colder climates, stiffly upright and spreading to 2-feet tall with a 3- to 5-feet spread.

Foliage/Texture: Fleshy, almost succulent gray green lanceolate leaves to 1- to 2-inches long, tapering to tip, nearly sessile, stems nearly succulent and exude a low grade white rubber latex; medium texture.

Flowers & Fruits: Yellow flowers aging to orange are encased in dominant fused yellow sepals clustered at branch terminals, sepals turn green and then light reddish-brown as they age and senesce; fruits are green and multi-carpulate.

Seasonal Color: Yellow flowers in spring

Temperature: Heat loving, cold tolerant to 10o to 20oF.

Light: Full sun will promote a tight and rounded canopy. Partial shade will cause stems to elongate. In Phoenix, silver spurge does poorly in full shade.

Soil: Tolerant of soil alkalinity and thrives best in well-drained soil; mildly salt sensitive showing as apical tip necrosis on older leaves.

Watering: Infrequently regular irrigations are necessary during summer, but no supplemental water is needed during winter.

Pruning: If overly irrigated and mature (plump and expansive like so many contemporary Americans), silver spurge can and probably should be cut back severely during early fall to rejuvenate growth.

Propagation: Seed, softwood stem cuttings.

Disease and Pests: None, except rot root if soils are irrigated and poorly drained.

Additional comments: Silver spurge is a reliable, low-growing accent plant for Phoenix xeric landscapes. Its flowers strongly attract bees. As with all Euphorbias, the latex sap is poisonous and might cause a mild skin dermatitis upon contact.

Taxonomic note: Euphorbia is a very diverse genus, even containing the popular pot plant, poinsettia. There are at least 2000 recognized species, many of which make fine landscape shrubs and subshrubs.