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
Sunset 4-24
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.
