Euphorbias, a very diverse species of plants, belong to the spurge family (Euphorbiaceae). The spurge family has more than 7,000 species, including crotons (Codiaeum variegatum), firecracker (Jatropha integerrima) and the Chinese tallow tree, or popcorn tree (Sapium sebiferum). The genus Euphorbia includes about 2,000 species of annuals, perennials, shrubs and trees.
Euphorbias vary in type greatly, from cactuslike succulents in hot climates to leafy plants in cooler regions. Leaf types range from the tiny deciduous leaves that arise between the stem spines of the candelabra cactus (Euphorbia lactea) to the 7-inch leaves of the popular poinsettia (Euphorbia pulcherrima). A common characteristic of Euphorbias is the poisonous milky latex, or sap. Euphorbia flowers, botanically called cyathia, are reduced clusters of flowers that resemble a single flower.
Depending on the species, use Euphobias in borders, as accent plants, specimen plants, potted or patio plants. Crown of thorns (Euphorbia milii) is used as a houseplant in high light conditions. Poinsettias are common potted plants, especially during the winter holiday season. Some species of Euphorbia are used for medicinal purposes.
The diversity of Euphorbia makes cultivation generalization difficult. Provide similar conditions to a particular plant's natural habitat. Most Euphorbia species prefer well-drained soils in full sun conditions. Propagate some Euphorbias by seed or by division, and others by stem-tip cuttings. Most propagate and root easily.
Poinsettias, hardy in USDA zones 10 and 11, flower from winter to early spring. Grown outside, poinsettias can reach 10 feet tall and 10 feet wide. Their inconspicuous flowers are surrounded by colorful, petal-like bracts.
Euphorbia myrsinites subsp. Pontica is a rock garden plant requiring light, well-drained soil. Its blooms are yellow-green and tinged with red during spring and it is hardy in USDA zones 5 through 9.
Euphorbia x martinii, a distinctive chartreuse-colored plant, grows 36 inches tall and is hardy in USDA zones 7 through 10.
Consider the poisonous sap when planting Euphorbias around children and animals. Use gloves or wash hands thoroughly after pruning or handling. Pest problems vary by species. Some Euphorbias, like crown of thorns, have no serious pests. Root rot is a problem for Euphorbias grown in poorly draining soil.