Euphorbia cyparissias - Spurge

The Euphorbia cyparissias, also known as Cypress Spurge or False Cypress Spurge, is a deciduous perennial with fine, bluish-green foliage that turns a beautiful yellow-orange color in autumn. It has a spreading habit and quickly forms a vigorous ground cover adorned with abundant, airy flower spikes in a bright yellow-green color in spring. This very hardy and prolific plant, sometimes invasive, requires space, wild and exuberant companion plants, a sunny location, and well-draining soil in a rock garden or on a slope.

The Euphorbia cyparissias belongs to the vast family of Euphorbiaceae. This species is native to southern, central, and western Europe, where it grows on cultivated land, along paths and fallow areas, in open terrain. This rhizomatous perennial plant, which develops from a creeping stump, produces numerous stolons that give it a spreading habit. It reaches a height of 30 cm (12in), 40 cm (16in) when flowering, and spreads to a minimum diameter of 50 cm (20in). From spring onwards, it produces numerous herbaceous stems covered with fine, brush-like foliage that resembles a cypress seedling. The color of the foliage changes from tender green in spring to bluish-green in summer, and finally to orange in autumn. The flowering stems appear between April and June, covered with narrowly linear leaves (1 to 3 mm (0in) in diameter and 1 to 4 cm (0 to 2in) in length), slightly curved. They bear umbels of petal-less flowers with yellow-green bracts that turn reddish with time. The stems and leaves contain a milky, sticky, and toxic sap.

The Euphorbia cyparissias will thrive in a dry and sunny rock garden or on a wild slope where it won't smother its neighbors. It can be an invasive plant, so it is best to associate it with other ground covers such as Achillea crithmifolia, Stachys lanata Big Ears, Veronica Georgia Blue, and Artemisia canescens. It will create beautiful patches of light at the base of shrubs, perennials, or dark-foliaged grasses such as Black Lace Elderberry, Berberis thunbergii, purple sage, Pennisetum Purple Majesty, and tall sedums like 'Black Jack' or 'Chocolate'. Its flowering period pairs well with the blue of creeping rosemary, perennial flax, and Goniolimon tataricum.