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Crown of Thorns, Euphorbia milii
Crown of thorns is similar to the bougainvillea in that what appears to be flowers are actually bracts. The red bracts are displayed throughout the spring and summer. Crown of thorns max out at about three feet, but it takes time as they are slow growers. The stems are armored with thorns, as the name implies.
Crown of thorns make a beautiful display around trees like below the ligustrum shown here.
Did you know crown of thorns are in the same genus as poinsettias?
Certified Arborist #1249A