Spurges Large and Small
from September 2001
We have had a long acquaintance with the spurges, or euphorbias. Some of the annual ones are cursed as weeds. One of the shrubby species, the poinsettia, is an essential part of an American Christmas. And just a few of the perennials have been grown by a small number of adventurous gardeners in California for many years. But only recently have Californians begun to recognize their rich variety.
There are around 2000 species in the genus Euphorbia, covering plant categories from annuals to trees, with some bizarre succulents in between. Those of particular value for California gardens are the hardy and semi-hardy shrubs and herbaceous perennials, particularly those from the Mediterranean region. In spite of a wide range of sizes and growing habits, these share several ornamental features. The leaves are usually simple (without lobes or divisions) and closely set around the stems in whorls or spirals. At the stem ends during flowering season (which for some can be most of the time) are intricate, often umbrella-shaped clusters of small, petal-less flowers. What we perceive as "flowers" are usually colored leaves or bracts at one of several levels, from the bases of the clusters to their ultimate divisions. These may remain colorful (or even grow more so) long after the flowers have passed. A feature hidden until some part of the plant is cut or broken is the milky sap, which is usually poisonous to some degree, sometimes violently so (see the plant descriptions below). Those of us engaged in pitched battles with gophers, deer and rabbits will appreciate this feature, for it makes many euphorbias nearly immune to attack. However, those of you with small children will want to wait to plant them until the age of testing each new object in the mouth has passed.
The euphorbias have many garden uses, varying according to size and cultural tolerances. Some of the largest and most dramatic, like E. characias, are displayed like specimen shrubs or used in the background in mixed borders. Those of medium and smaller height add an unusual touch to the border and are also useful, en masse, for ground cover. Several are notably drought tolerant, giving them additional uses on dry banks and other exposed, neglected spots. Regardless of their water needs, most of them appreciate, and show their best color in, sun at least part of the day. Most thrive in a wide variety of soils, as long as they are not soggy for extended periods (this is particularly important in hot weather). They need little maintenance, other than the shearing of spent flower clusters and occasional removal of older stems. Long-handled tree loppers and heavy gloves are important equipment when practicing this on the stouter-and more toxic--species, which "bleed" profusely when cut. All of the following are hardy to 10oF. or less.
E. amygdaloides, wood spurge, is a perennial with clustered, erect stems from a narrow base. It can grow over 2' high, though the cultivated forms are usually smaller. Deep green leaves up to 4" long are loosely set around the stems. The flower clusters are open and rise well above the foliage, showing bright lime-green "flower leaves". 'Purpurea' is a relatively short, dense form with reddish stems, beautifully purple-tinged leaves and some purple shading in the flower clusters. The flowering season extends from mid-spring into summer, at least along the coast.
This is a fine border perennial, thriving in sun or part shade near the coast but best with at least afternoon shade inland. Moderate watering.
E. ceratocarpa is a more open plant, also nearly erect, with slender stems rising two to five feet. It has rather loosely set, narrow pale green leaves, up to 3" long, with conspicuous lighter midribs. It has a long flowering season beginning in late spring, displaying broad floral sprays with cheery yellow leaves and bracts at the shoot tips.
This species is easily grown in sun or light shade, with moderate watering.
E. characias is one of the true spectacles of the group, though it is definitely not for everyone. The plants are nearly shrubby, sending up several thick, leafy stems, 2-5' high, from a woody base. The leaves are up to 4" long, rather narrow and colored an unusual blue- or grey-green. In late winter and early spring the flower clusters unfold at the tips of second-year stems, becoming broad towers as much as a foot long. The floral leaves and bracts are painted brilliant chartreuse to yellow and hold their color well for several weeks after the flowers have gone. The little flowers themselves are bright green, making a pleasant contrast. The subspecies wulfenii is even larger, in all its parts. The cultivar 'Portuguese Velvet', evidently from the type species, is considerably smaller and distinguished by darker, greener leaves with a particularly velvety surface. It also has the odd habit of producing small plantlets at the ends of the flower stems, providing an easy means of propagation.
These are not long-lived perennials, but they set generous quantities of seeds, which are easily started as the weather cools in fall (more likely, they will simply volunteer here and there around the garden). They should have a sunny spot and well-drained soil. Only a few deep waterings each summer will suit them nicely. Handle with care! The juice can raise blisters on the skin and could cause serious eye damage.
E. cyparissias is perhaps my favorite of the group. It travels slowly in all directions by rhizomes and makes broad, billowy mounds up to a foot (or slightly more) high. The slender stems are well branched and lined by brushes of very narrow 1-2" leaves, giving a delicate appearance. The leaves are bright to light green or blue-green in color. For several weeks in late spring and summer it is nearly covered by umbrella-shaped flower clusters showing bright greenish yellow bracts. 'Fen's Ruby' is a particularly short, dense selection with blue-green leaves, strongly tinged with purple in new growth. All forms are winter-deciduous in colder climates.
These are delightful plants for borders, ground cover and open banks, in sun or light shade. While it performs best with moderate watering, it is fairly drought tolerant. You will probably have to rogue out some volunteer shoots and seedlings in unwanted places.
E. epithymoides (polychroma). I tried this little perennial long ago, finding it the only species then available from eastern growers. I suppose that it helped spark my interest in other euphorbias. This is a particularly hardy and winter-deciduous perennial, mounding to a foot or more high. It has many soft, slender stems clothed in oval 1/2-1" bright green leaves. These take on beautiful red and orange hues in late fall. The flower clusters are small and nearly flat, with yellow to chartreuse floral leaves and bracts. They are borne over many weeks in late spring and summer.
E. dulcis. I know this species only through the cultivar 'Chameleon', which is a truly showy perennial. The typical form is fairly undistinguished, and I will not describe it here. 'Chameleon' slowly forms sizeable colonies by underground rhizomes. The slender, reddish stems rise a foot or more, carrying brushes of narrowly oval, vivid purple leaves 1-2" (or more) long. The flower clusters are small and combine purple and green shading. They are actually less interesting than the leaves. Fall color of the foliage is bright red, the plants dying to the ground in cold winters.
This is a choice border perennial, though needing occasional control. It should have moderate to regular watering but is otherwise undemanding.
E. x martinii. This is a hybrid between E. amygdaloides and E. characias, both described above. The sturdy, upright stems and thick, narrow leaves resemble those of E. characias, but their beautiful reddish purple shading when young and the smaller plant size suggest the second parent. The flower clusters are elevated well above the foliage and several inches long, with bright green to chartreuse leaves and bracts. 'Red Martin' is alleged to have more vivid coloring than the unnamed selection in general circulation; I have found it a stiffer, more open plant, showing about the same coloration in our climate.
For those of us cursed with heavy soil, this hybrid will be easier to grow than E. characias. It thrives in either sun or light shade, with moderate to occasional watering.
E. myrsinites is unusual in habit, color and texture. The thick, light green stems radiate from a compact crown, spreading or even pressing against the ground. Neatly arranged around them are striking silvery grey, pointed-oval leaves about an inch long. Tipping the stems in spring or early summer are rounded flower clusters shading in color from grey in the lower leaves to pale chartreuse or yellow in the end bracts.
This is a tough, undemanding plant, useful either alone or in small drifts. It is remarkably drought tolerant. Like E. characias, it has highly irritating sap and should be handled with extreme care.
E. robbiae is also known as E. amygdaloides var. robbiae (or 'Robbiae'). This is a rhizomatous perennial, making thick colonies. The individual stems are erect, 1' to nearly 3' high (probably closer to 1' in our current form) and have broad, whorled leaves. The leaves are thick and leathery, deep green and shiny above, paler beneath. The flower clusters are rather open, with light green leaves and bracts.
This is a plant for either borders or small-scale ground cover. It is shade tolerant and thrives with moderate watering.