This week’s Friday Tree was tricky. Some of you got it, and some of you were very close. The two reasonable guesses were Catalpa, Catalpa speciosa, or desert-willow, Chilopsis linearis. The flowers of both these trees are similar, and they are closely related, but they occupy very different habitats: catalpa is a midwestern tree of moist forest, while desert-willow is a shrub or small tree found on desert waterways in the American west.
This tree is Chitalpa, xChitalpa tashkentensis, a hybrid between to different genera of tree, Catalpa and Chilopsis. The one shown here is called “Morning Cloud” and genetic analysis shows that is Catalpa speciosa x Chilopsis linearis. Hybrids of two genera are extremely rare.
The hybrid was created by A. Russanov of the Botanic Garden of the Uzbek Academy of Sciences in Uzbekistan in 1964. However, the two parents are from the eastern US (Catalpa speciosa) and the western US (Chilopsis linearis).
The tree in these pictures is the only one I have seen in Kentucky. It has very peculiar leafing and flowering dates, leafing out in late May or early June and flowering from July to September.