There are two katsuras in the Park, a female in the east triangle and a male in the southeast triangle. See Wikipedia entry here.
Cercidiphyllum is a genus containing two species of plants, both commonly called katsuras. They are the sole members of the monotypic family Cercidiphyllaceae. The genus is native to Japan and China.
Female katsura in the east triangle in July
Katsuras are dioecious, meaning that some individual trees have male flowers and some have female flowers. Only the female trees have seed pods.
As the scientific name suggests, these trees are from east Asia.
The scientific genus name, cercidiphyllum, means having a leaf like the genus Cercis, the redbuds. Compare the katsuras with the numerous redbuds in the Park. Redbud leaves are alternate, not opposite on the stem.
The leaves reportedly have a strong scent in the autumn, sweet like cotton candy or burnt sugar. See if you can smell it during leaf fall!
The leaves turn yellow-orange in autumn
The seed pods look like tiny clusters of bananas along the branch, and the seeds are released in late autumn or winter
There is a male katsura at the Morris Arboretum that might possibly be the largest katsura in North America.
Female katsura in the east triangle with seed pods along branch
Note heart-shaped leaves with edge striations. July photo.
Male katsura (no seed pods) in the southeast triangle in July photo
A katsura branchlet with leaves and seed pods in the middle, flanked by branchlets from two different redbuds with their corresponding seed pods. Though all the leaves are heart-shaped, the redbud leaves alternate on the branchlet and have longer stems.
Note the purple color of both leaves and seed pods from the redbud on the right, which is from the only redbud in the west triangle. Photo taken in July.
Summary of the physical characteristics of the katsura tree
Female katsura in November, without leaves but covered with thousands of mature brown seed pods
One of the thousands of banana-like seed pods in November, with the contents of another seed pod: about two dozen tiny winged seeds.
There are two katsura species: C. japonicum has seeds winged only at one end, as seen here. C. magnificum has seeds winged at both ends.
Katsura at the Morris Arboretum.
This male tree, planted in 1902, is thought to be the largest katsura in North America. Photo credit here.
Botany 101 Bonus
Have you ever heard the terms "native," "exotic," or "invasive" plant? A plant native to the United States has been here for hundreds of years, and most definitions state that native plants were here before the Europeans first came to the land that was to be the United States. Any plant brought after that time is a non-native or introduced species. The term exotic is similar, but means a plant that has recently been added to a continent from another continent. Many of these non-native plants were brought here accidentally as seed mixed in with cargo, but many were brought intentionally by humans for humans. The katsura is a non-native plant brought to this country for use as an ornamental tree.
Just south of the male katsura, on the other side of the fence, is a tall paulownia tree (Paulownia tomentosa, Royal Empress Tree), and there is another one on the east side of the 19th Street bridge next to the Park. There are also many paulownias in Logan Circle circumferentially arranged around the fountain. Like the katsura, this tree species is native to China. It produces beautiful blue flowers before leafing out with very large leaves in the spring, and was brought to the United States for use as an ornamental. It will grow in almost any soil, produces millions of wind-scattered seeds, and is fast-growing. These same characters have allowed it to spread to the detriment of native ecosystems and it is considered an invasive species. It crowds out other species with its rapid seed germination and shades them out with its fast growth and huge leaves. Connecticut has banned the sale of paulownias for this reason. One reason paulownias are prominent along railroad tracks (and former railroad tracks like in the Callowhill Cut) is that the soft seed pods were used as "packing peanuts" around Chinese porcelain before styrofoam. These seed pods would rupture and release their seeds during rail transport.