In 1996, controlled crosses were made among the species from which reproductive specimens are available in an effort to determine interspecific crossabilities and to generate progenies for further use in developing trees with superior tolerances to environmental stresses. Twenty trees growing at four arboreta and representing nine species were used in 49 controlled crosses. Inferences about crossability were made based on numbers of fruit filled and support for hybridity is derived from intermediate leaf morphologies. Carpinus , interspecific hybridization, crossability, environmental stress tolerance, tree breeding. Members of the genus Carpinus possess such understated elegance that they are often overlooked in the process of selecting landscape plants.
Closer inspection reveals attributes of considerable value for urban trees.
In spite of our limited knowledge of this group, there is a growing body of evidence that the species that comprise this genus possess a wide variety of adaptations which would be useful in coping with urban stresses. Without exception they also possess ornamental traits of considerable variety. In 1996, while working for the Landscape Plant Development Center, the senior author began a project of making interspecific crosses among the available species of Carpinus. The goals being to determine cross compatibilities and produce hybrids which could be evaluated themselves and also ultimately used to create a second generation of trees. From these F2 progenies, individuals would be selected for possessing the desired combination of traits from the original species.