Aransas/San Patricio Master Gardener Poinsettias, pencil trees, crown of thorns and spurges are just a few of the common genus Euphorbia that add novelty and interest to your garden while requiring little care. With over 2000 species this family includes annuals, biennials, perennials, shrubs, trees, and succulents. Some are prized for the colorful bracts that surround insignificant flowers such as poinsettias, others for their cactus like form such as the crown of thorns. Many are succulents which mimic cacti in their appearance and are equally diverse in their form and size. Easy to grow in well drained soils, they are deer resistant, and most require little water or care. They like bright light during the summer but must be protected from winter frosts and freezes. Therefore, it is advisable to keep them in pots which can be moved inside.
All euphorbia ooze a milky white sap when damaged or cut that can be irritating to the skin or toxic if ingested. The intensity of the toxicity varies by species. Wetting the plant’s wound with water will cause this sappy latex to coagulate. When cutting for propagation, dipping in boiling water or holding the stem briefly to a flame to prevent latex bleed is advisable. The tips should be allowed to dry for a couple of days before propagating.
The favorite plant around Christmas is Euphorbia pulcherrima or poinsettia. This plant is named after Joel Roberts Poinsett, the first US ambassador to Mexico, who introduced it to the US in 1825. The poinsettia is a native plant to the Pacific coast of Mexico and Central America and can grow from 2 to 16 feet tall. This is a subtropical plant and requires a temperature between 50 to 70 degrees F to remain healthy. It prefers moist soil but not wet feet. It is difficult to induce to reflower so they are best bought annually. This plant is not as toxic as its reputation claims unless one is extremely sensitive to the latex and may suffer an allergic reaction. Poinsettias, if ingested, may cause diarrhea or vomiting in animals and humans.
Euphorbia tirucalli, known as pencil tree or milk bush, is an interesting plant that has a series of single and multiple trunks that support pencil-thick succulent branches. It is the branching and not the insignificant flowers that make this plant compelling. The tiny leaves appear on the tips of the branches. It can reach a height of 30 feet tall and 6 feet wide in a tropical climate.
One variety, ‘Sticks-on-Fire’ has pale pink to salmon pink stems with new growth being very intense in bright light. You need to keep the milky sap off your fingers and away from your eyes as it can produce severe eye damage. In many cultures it is used medicinally to treat cancers, tumors, warts, asthma, rheumatism, and other illness. It is also said the sap can be easily converted into a fuel equivalent to gasoline.
Euphorbia milii commonly known as crown of thorns or Christ plant, a spiny shrub, is one of the most popular euphorbias. It can get 3 to 4 feet tall and is armed with (1 inch) spines on all sides. At the tips of stems are clusters of bright green 2-2 ½ inch leaves. Tiny flowers are surrounded by either bright red or yellow bracts, which look like petals. Clusters of these flowerlike bracts appear on the ends of the spiny stems. Flowering begins in early spring and will last through fall if kept in bright light. The beauty of this plant makes up for the inconvenience of the spines.
Cushion spurge, Euphorbia polychroma, grows from 1 to 2 feet high. The bright yellow hemispheric flowers are surrounded by whorls of yellow-green bracts. In the fall the display will transcend from yellow to orange to red. It is short lived but reseeds. It needs afternoon shade. Many of the spurges are considered to be pests and can be invasive.
Euphorbia tithymaloides, redbird cactus or Devil’s backbone, is a succulent spurge. It makes a wonderful houseplant. The bracts are pinkish-red and resemble small birds. The zigzag stems create interest and character and are covered with green or variegated two inch leaves. The variegated variety is more attractive but may occasionally produce a mutation stem of solid green leaves. It can grow to about six feet.
Texas A&M AgriLife Extension Service - Aransas County Office is located at 892 Airport Road in Rockport. AgriLife Extension education programs serve people of all ages, regardless of socioeconomic level, race, color, sex, religion, handicap or national origin.