Trifoliate Orange (Hardy Orange or Flying Dragon)
Still available in the horticultural trade, Trifoliate Orange spreads aggressively once planted, outcompeting the diverse native vegetation valuable to birds and other wildlife. It is more widespread in the South and Southwest but is becoming more of a problem in North Carolina. The orange-like fruit produces many seeds, which are widely dispersed by mammals. Once established, it forms impenetrable, many-stemmed, thorny hedges over 6 feet tall, completely dominating the shrub and herb layer.
Trifoliate orange is recognized by leaves-in-threes alternating up the stem and large (3-inch) thorns protruding from the stems. Stems are all dark green except in older parts of the hedge. Small white flowers and later small orange-like fruits (1-2.5 inches in diameter) appear in the spring. At first, the fruit is green then ripens to a bright yellow. The oranges with their many seeds fall close to the plant, producing multiple stems spreading each year to encompass more of the ground. The fruit is carried away by mammals, which produces new colonies.
Fact Sheet: Trifoliate Orange