Since their introduction in the 1950's, horticultural professionals have become accustomed to referring to thornless mesquites as Chilean Mesquites and Prosopis chilensis. The actual botanical name of this specie has long been a subject of controversy in both scientific and commercial circles. However, several points seem undisputed: 1) the published literature is nearly unanimous in describing the tree as a hybrid, a cross or mating of two different parent types; 2) all the trees sold are either entirely thornless or have few or very small thorns and 3) an assortment of trees with widely varying physical and horticultural characteristics, but sharing the thornless trait, are sold as Chilean Mesquites.

Typically, about 25% to 50% of germinating seed collected from thornless mesquites produce thornless trees. The balance of germinating seeds produce varying numbers and sizes of thorns. Traditional hybrid taxonomy has never been used in the nursery trade because the actual parent types that produce thornless offspring are unknown. It seems clear that the genes (or gene) that suppress thorn formation are, by this time, wide spread among commercially produced trees sold as Chilean Mesquites.

Within the landscape industry, Prosopis chilensis and Chilean Mesquites have evolved to become trade terms with only limited botanical relevance. The assortment of shapes and forms of thornless mesquites has been of benefit to landscape architects and contractors by offering them the opportunity to select trees uniquely suited to a given landscape application. The growing acceptance of arid landscape trees, mesquites included, has fostered a demand for greater uniformity within desert species.

Efforts to increase uniformity of thornless mesquites have emphasized either vegetative/clonal propagation (rooting a small portion of the plant) or "pure" seed culture, where growers work with seeds that produce trees highly similar to the parent stock. While both methods improve uniformity both have limitations. Both methods rely on limiting the genetic diversity within the propagation stock.

Such limitation can be a double edged sword when the tree is installed in the landscape. Genetic diversity serves to protect plant populations from devastating attacks by injurious insects and diseases. Selection of parent trees for seed or clonal propagation tend to focus on the phenotype or external features of trees. Upright branching, dense foliage, trunk structure or rapid growth are examples of phenotypes growers might use in selecting parent stock. Appearance alone gives little indication of rooting habit, cold hardiness, disease and insect resistance or adaptability to varying soil or growing conditions.