The Citrus Orange is a variety of orange (citrus sinensis) with crimson, blood-colored flesh. The fruit ranges from small to medium sized; its skin is usually pitted, but can be smooth. Blood Oranges owe their distinctive appearance to a pigment called anthocyanin not typically found in citrus, but common in other red fruits and flowers. Not only is the inside of the orange darkly pigmented, but the outside may feature dark washes of red. Good indoor bonsai tree.