Euphorbia rigida aka Upright Myrtle Spurge

Euphorbia rigida is an evergreen perennial in the spurge family. Its common names include rigid spurge and gopher spurge. It comes from southern Europe, southwest Asia, and northwest Africa. The plant forms a bushy clump with upright, rising stems. Garden plants reach 1–2 feet [0.3–0.6 metres] tall. They spread 2–3 feet [0.6–0.9 metres] wide. RHS lists a smaller spread, up to 1.6 feet [0.5 metres]. Plants take about two to five years to mature.

Thick green stems bear close spirals of blue-green leaves. Each fleshy leaf has a lanceolate shape and pointed tip. The leaves have smooth edges and no hairs. In fall, the foliage takes on red and bronze tones. Cold winds can spoil the leaves, though the plant stays evergreen. Flowering stems die back after their blooms fade.

Flowers appear from April to June at the shoot tips. The small greenish flowers sit within bright yellow to chartreuse bracts. These bracts provide most of the spring color. The flower heads form rounded clusters above the leaves. Bees visit the blooms. Small, lobed green capsules follow the flowers. These oval fruits hold smooth, white, oval seeds.

Grow rigid spurge in full sun with good soil drainage. It also accepts some shade. Light loam suits it, including poor, sandy, or rocky ground. RHS also lists chalk and clay where drainage is good. The plant accepts acid, neutral, and alkaline soils. It tolerates drought, salt, and dry soil. Sources give USDA zones 7–10, with NC State extending this to zone 11. RHS rates its UK hardiness H6. Plants may live shorter lives where winters stay warm.

Use it in rock gardens, gravel beds, and dry borders. It also suits coastal sites, slopes, banks, and patio pots. Deer resistance adds value where browsing is a problem. It has few serious pest or disease problems. Plants can self-seed freely and become weedy in undisturbed ground. Remove faded flower heads to limit unwanted seedlings. Division, seeds, and stem cuttings offer ways to raise plants. Routine pruning is not needed.

Do not eat any part of this plant. Its milky sap can cause skin rashes and mouth blisters. Sap in the eyes can cause lasting damage. Wear gloves and protect your eyes when handling it. Keep plants away from children and pets.