Barbara J. Euser
In my friend’s Tiburon garden, Mediterranean spurge spreads across a shaded hillside. When I admired their chartreuse flower bracts, my friend suggested I dig up a few young plants and take them home. “I put in two small plants a few years ago, and now look at this,” she gestured widely with her arms.Also known as Euphorbia characias,withsubspecies wulfenii (from Turkey and the Balkans) and characias (from Portugal and Spain), Mediterranean spurge is native to the Mediterranean region and thrives in the Bay Area’s Mediterranean climate.The genus Euphorbia comprises over 2100 species: just over half are succulents, some resembling cacti with tall branches covered with spines. Succulent euphorbias are native to north and south Africa and the middle east. The remaining 45 percent are not true succulents and include such plants as popular Christmas poinsetttias. All euphorbias are characterized by their white, milky sap. The sap contains toxic terpene esters, which can irritate the skin and damage eyes, so take care when cutting or handling them. However, the plants also have medicinal properties: Euphorbia pekinensis is one of the fifty fundamental herbs in Chinese medicine. Carolus Linnaeus assigned the name Euphorbia to the genus in honor of the Greek physician Euphorbus. Over two thousand years ago, Euphorbus reportedly used one of the species, possibly Russian spurge, as an herbal remedy to cure King Juba II of Numidia of a swollen belly.With its slender, fleshy, blue-green leaves and chartreuse, cushion-shaped bracts, Mediterranean spurge grows from two to five feet tall, two to three feet wide, and makes an attractive addition to a garden border. A plentiful self-seeder, it can also be used as a ground cover. It blooms in spring and early summer, then tends to fade into the background by mid-summer. Its evergreen foliage remains attractive year round. The flowers are insignificant and have no petals. It is bracts, that is modified leaves, that add dimension and color to the flowers. The bracts contain nectar glands that attract pollinators.While driving along a country road in Greece, I was struck by the number of Mediterranean spurge I saw. They grow wild along the shoulder and on the rocky hillsides here. Only drought resistant plants survive in the hot, harsh environment. The main requirement of this hardy plant is well-drained soil. Heavy soil may cause its roots to rot. Although it has adapted to difficult conditions, in the friendlier conditions of a garden, it will thrive.The influential garden designer Gertrude Jekyll (1843-1932) referred to Mediterranean spurge as “one of the grandest and most pictorial of plants.” Popular among gardeners in the southern Mediterranean for generations, Euphorbia charcarias is adapted to a variety of conditions and can tolerate temperatures below zero degrees Fahrenheit, as long as the soil remains dry. To fill different niches in the garden, a number of cultivars have been developed, including ‘Ember Queen’ with variegated foliage, the compact ‘Humpty Dumpty,’ the strikingly blue ‘Jade Dragon,’ and the robust ‘John Tomlinson’ with spherical bracts 16 inches in diameter. The related species Euphorbia amygdaloides var. robbiae is well adapted to dry shade. Especially useful as a ground cover, its glossy dark green leaves form a spreading mound. In the spring, panicles of yellow flowers seem to float above the leaves. Topping the list of purple-leaved perennials is Euphorbia dulcis, a sun-loving chocolate-looking plant that contrasts spectacularly with spring’s bright greens.One caveat— Euphorbia esula, Euphorbia oblongata, and Euphorbia terracina are on the California Invasive Plant Inventory and should be avoided.If you would like to learn more about this extensive genus of plants, the International Euphorbia Society provides information on cultivation and propagation, as well as a photo gallery, on its internet site.