CYPRESS SPURGE AKA Euphorbia cyparissias
During the 1860's Cypress spurge was imported from Eurasia for its decorative appeal. Likely because of its low maintenance nature, it was frequently planted in graveyards, so much so that one of its common names is graveyard weed. Cypress spurge is a groundcover with fine narrow leaves growing in alternate pairs along the stem that eventually form whorls along the upper portion. When in bloom, the plant is loaded with an abundance of small pretty yellow flower clusters giving it a very attractive appearance. Another of the plants characteristics is the milky substance that is exuded from the stem or root when either are broken. This toxic lactic substance can cause contact dermatitis in some people. Originally intended as an ornamental groundcover, the plant readily escaped cultivation and has now achieved its present outlaw status. The plant is considered potentially toxic to horses and cattle, though most grazing animals will instinctively avoid it. When I started one of my gardens, shortly after moving here, I noticed this volunteer plant growing along the back edge. I welcomed it and encouraged it to grow. Quickly realizing that it did not need any encouragement, my intentions changed, and I began trying to eradicate it. It has been over 20 years now and I have yet to become successful in that endeavor. The plant has a trailing rhizome type of root system that can reach up to ten feet. The root readily breaks off as you pull it and new plants form from lateral buds all along the remaining root segments; so, it continues to grow in the back of my garden along the tree line right next to the poison ivy adding another level to my exasperation. As you can imagine the plants abundant flowers eventually produce abundant seeds, up to three seeds to a capsule, and to make matters even worse, the mature seed pods explode propelling the seeds up to 16 feet away! Take my advice DO NOT ENCOURAGE THIS INVASIVE VINE! As is true of all invasive non-native plants, the aggressive growth of Cypress spurge crowds out native species. Because of the lactic substance exuded it is not considered a grazing plant, in fact this plant not considered beneficial for any of our native wildlife.
HOW TO REMOVE
If this plant is growing in your garden, you can attempt its eradication by pulling it. You can contain the spread this way but if you don't pull out the entire root the plant will continue to exist in your garden. Though I have not had an issue with contact dermatitis, I suggest wearing gloves to prevent possible a possible occurrence from contact with the sap. The most effective control method is to apply an herbicide such as glyphosate. You will likely need to repeat application during the growing season. If Cypress spurge is growing in your lawn or in a horse or cow pasture, the recommendation is repeated mowing every 21 days after the first bloom. It is important to continue the 21 day mowing process as mowing encourages new growth. If the plant is already in seed mow around it so as not to encourage further spread of the seed. Eventually consistent mowing during the plant's growing season should deplete the plant of its growth energy. Another herbicide you might consider is 2,4-D amine. The first application should be at early bud stage. A second application will be needed during the plant's growing season. This can be a difficult plant to eradicate in a livestock pasture setting.
Biologic control
There are at least two insects that will help to limit growth of the plant. The brown dot leafy spurge beetle Aphthona cyparissiae, and the black leafy spurge flea beetle Aphthona lacertosa. These insects lay their eggs at the root base of the plants. The larvae feed on the roots and the adult beetles feed on the foliage. Actually, there have been 11 species of European insects released in North America to help control this plant. It seems none have found the Cypress spurge in the back of my garden, at least not yet!