Saturday, December 30, 2023

Chitalpa tashkentensis, a popular intergeneric hybrid tree

 Chitalpa tashkentensis is a popular flowering and shade tree. It is wide-spread across California and can be found in most landscaping nurseries.

The reason I decided to write about it is that there is a very limited and often erroneous information about this tree (on the English speaking web). I myself got this tree as a 5-6 ft whip in 2001 because I was looking for a flowering tree with fast decomposing leaves. Now, over 20 years later it is a well developed tree that provides light shade for my front yard plants. Below are the day and night pictures from June of 2023.

Only after getting home I checked the tag on this plant and noticed the species name, tashkentensis, which corresponded to the capital city of the country I was born in. Tashkent is the capital of Uzbekistan. The genus name happened to be a combination of two different genera, Catalpa and Chilopsis. Here I had an intergeneric tree somehow related to Tashkent, now planted in my front yard in California.  I had to figure out why it was named that way.

The searches quickly took to me to the origin of the tree, Tashkent Botanical garden.  However it took me a bit more researching to figure out the Chitalpa's breeder name.  The problem was that there were two great breeders working in this garden, Fedor Rusanov (1895-1979), and later his son Nikolay Rusanov (1938-2017). The most noticeable creations of  Fedor Rusanov are the hybrid hibiscus plants from three American species and his hardy interspecific yucca hybrids.  I will cover the hybrid hibiscus of Fedor Rusanov in another post. 

Now back to Chitalpa. Chitalpa was created by the son, Nikolay Rusanov in 1964 by cross-pollination between Chilopsis linearis and Catalpa bignonioides. I could not find the info on the directionality of his cross(es).  In the end, he selected seven cultivars, five with pink flowers, and two with white flowers. Two selections, 'Pink Down' and 'Morning Cloud' made its way to the US via Robert Hebb of the New York Botanic Garden in 1977. Only in 1991, Thomas Elias and Walter Wisura from the Rancho Santa Ana Botanic garden created the name Chitalpa tashkentensis and applied it to both selections. 

This tree is completely sterile and propagated vegetatively through cuttings or root sprouts. 

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