Hybrid plants are generally created by pollinating two different generic plants that results in drastic plant improvements, one of the improvements being very fast growth, that has been defined to mean: Hybrid Vigor. The hybrid creation usually genetically unites the best characteristics of both parents, and frequently the created hybrid can have much superior characteristics than either of the parents possessed. The Mule palm tree gets its fast growing trait from the Queen palm, along with the gray, slick trunk, and the 10 foot long leaves - with up to l50 leaflets - that are colored with a dark green much like the Queen palm, but they are gracefully arranged, curved and drooping with a feather-shaped leaf like the Pindo palm tree. The pollen (male) parent from the Queen palm is always hand pollinated onto the female parent, the Pindo Palm. The Mule palm tree develops into a dramatic, graceful palm appearance, often described as looking like a Coconut palm tree, a tree that is not unfortunately cold hardy. Adult Mule palms are moderately cold hardy and have been documented to survive temperatures as low as 16 degrees F. in landscapes of North Carolina, Texas and Washington State.The original mule palm was produced by hand pollinating the Queen palm (male) tree, Syagrus romanzoffiana pollen onto a Pindo palm , Butia capitata (female), and subtle variable trees have appeared in some of the seedlings, however, generally the seed grown trees conform to the original cross in terms of the cold hardiness and cellular characteristics of the above ground morphology. The reverse cross of this hybrid tree has been found generally to offer poor results in surviving for very long into commercially acceptable hybrids. Adult Mule palms can form pink flowers, but the seed are usually sterile, and those creations that have rarely sprouted are unacceptable in commerce. There have been rare instances when mule palms were being accidentally produced from palm collector gardens, where a Queen Palm tree was planted up close to a Pindo palm tree, and the viable seeds then fell to the ground and sprouted. Mule palm trees flourish in well drained soil profiles and are adaptable in sandy soil or clay, and are generally tolerant for droughts for limited periods of time. There have been online reports of Mule palm trees being grown in Alabama, Georgia and South Carolina, and of course, they have not faced the demands of being cold hardy where Mule palm trees have grown for years in California, Florida and Louisiana.