Ginkgo biloba ‘Sky Tower™’’JN9’ syn. ‘Sky Walker’ is male. The origins of this introduction were not known until an email conversation with Gary hand of Handy’s Nursery. He said “One last bit of info on the plant patented under the name Ginkgo biloba ‘Sky Tower’, that plant was found at a truck stop in southern OH (before the patent) and is also synonymous with Ginkgo biloba ‘Grindstone’, Ginkgo biloba ‘Grindstone Lake’ and Ginkgo biloba ‘Fly Fastigiate’. The tree names Ginkgo biloba  'Sky Tower' or the ‘Sky Tower Ginkgo’ is a popular tree for tight spaces where upright tight growth is desirable.
 
Description - Ginkgo biloba ‘Sky Tower™’’JN9’ syn. ‘Sky Walker’. The leaves of this plant are typical of the species, what sets it apart is that it is a slow, very dense and narrow growing tree. After 10 years of growth it becomes 1.5 m high and 1.2 m wide but ultimately 4.5 - 6 m high and 2 to 3 m wide can.