Latin name of the genus and species of the plant claimed:Zelkova serrata.

Variety denomination: ‘JFS KW4ZS’.

BACKGROUND OF THE INVENTION

In 2001, I began a program to create improved cultivars of JapaneseZelkova, Zelkova serrata.I searched through thousands of seedlings ofZelkova serratagrowing in nursery rows in Canby, Oreg., Independence, Oreg., and Boring, Oreg. I walked along each row, looking for significant seedling variation that might hint at a unique and improved cultivar. From this search, I selected 50 seedling trees. The present tree was selected as an open pollinated seedling among seedlings ofZelkova serrataseedlings in Boring, Oreg. I marked and labeled this new tree, ‘JFS KW4ZS’, to be transplanted for further evaluation. It first caught my attention because it was more upright growing, with a sturdier trunk, better branching, dark green foliage, and a somewhat shorter internode length than typical seedlings of the species.

I dug this new tree during winter dormancy and transplanted it, along with the 49 otherZelkova serrataseedlings that were selected in this process, in a special evaluation row in the Boring, Oreg. nursery. During the summers of 2002 and 2003, I continued to evaluate this tree in comparison to the other special seedlings I had selected as well as typicalZelkova serrataseedlings. I became convinced that this tree had unique and improved characteristics that would be valuable as a cultivar in the nursery and landscape trade. In February of 2004, I transplanted ‘JSF KW4ZS’ and four other seedlings from this group of 50 into a special long term block where the spacing would allow it to grow to a larger and fuller form. The remaining 45 seedling trees were destroyed. Of the five trees planted in the long term block, one is ‘JSF KW4ZS’, one is ‘JFS-KW1’ U.S. Plant Pat. No. 20,996, and the other three were rejected and destroyed. Over the next several years, I continued to examine and evaluate my new tree in comparison to both seedlings and existing commercial cultivars of the species.

In August, 2011, I began a program to test asexual propagation of ‘JFS KW4ZS’ in small field plots in nursery rows in Canby, Oreg., by chip budding onZelkova serrataseedling rootstock. I grew ‘JSF KW4ZS’ alongside existing cultivars ofZelkova serratafor comparison, namely ‘JFS-KW1’ (U.S. Plant Pat. No. 20,996), ‘Green Vase’ (U.S. Plant Pat. No. 5,080) and ‘Musashino’ (unpatented). I continued to direct that ‘JSF KW4ZS’ be chip budded in these small test plots in the Canby, Oreg. nursery, each year through 2017. A total of 93 test trees were produced in these plots. All of the test propagated nursery trees were destroyed after evaluation, except for 20 which I kept for stock increase. Evaluation of these asexually propagated trees demonstrates the valuable and unique characteristics of ‘JFS KW4ZS’ were firmly fixed in each successive generation.

BRIEF SUMMARY OF THE INVENTION

This new cultivar possesses a unique combination of characteristics that have proven firmly fixed in asexually propagated progeny and that comprise a combination of green foliage, and a more compact growth habit with a symmetrical upright branch structure.

