Learn to tell male and female trees apart for the beautiful and fragrant katsura tree.
Katsura gender key facts
Name – Cercidiphyllum
Reproductive type – dioecious
Male – white-pink flower petals with hanging pollen-sacks
Female – white-green flower petals with pollen-catching tentacles
The key is to look at the flowers. Male tree flowers are a distinctive pale-red color, whereas petals on flowers of a female tree are white-green-colored and harder to see.
Katsura, a dioecious tree
What is a dioecious plant?
- A dioecious tree or plant is one where individuals are either male OR female, but not both.
- For a female tree to bear fruit, it must be pollinated by a male tree (which itself won’t bear any fruit).
- A female dioecious tree will not release pollen, which is good if you’re sensitive to pollen or have allergies.
- It’s often possible, though, to graft a male branch onto a female tree and vice-versa. Fruits can thus form even if there aren’t any other trees nearby.
How to tell the gender of a katsura tree
So before you go ahead planting a katsura tree, take a look at the flowers.
The flowers are how to tell the trees apart clearly.
- Also, if you notice fruit pods forming, the tree is definitely a female tree.
Flowers of both Cercidiphyllum species are almost identical.
- There’s more variation between different varieties within a species, than there is between the two species.
- Picture at top shows a Cercidiphyllum magnificum female flower.
- Picture below shows a C. japonicum female flower.
- Third picture shows a Cercidiphyllum magnificum male flower.
- A picture of a Cercidiphyllum japonicum male flower is shown in our article about multiplying katsura.
Female katsura trees
- Both male and female flowers open up before any leaves have unfurled. Observing the flowers is thus very easy even though they’re small.
The petals form a sheath, and on female flowers they never really open up.
From within this sheath, several long, twirly “styles” extend. They look like tentacles close up!
The style is the part of the female flower that collects pollen from the air and channels it deeper into the flower to the ovary. The tip of the style is called the “stigma”, and it’s usually very sticky for pollen to adhere to.
- Similar thread-like styles appear on more common plants, like corn.
- The silks at the end of an ear of corn have the same function as the styles on the katsura tree female flower.
- It’s a typical feature of plants that are wind-pollinated.
- Air flows through very easily, dropping off whatever male pollen it carries from afar.
Male katsura trees
- These stamens are long to make sure no pollen gets trapped in the sheath formed by the petals.
This wind-pollinated tree decided it wanted to travel far!
- Indeed, it blooms even before unfurling any leaves.
- This helps air and wind circulate very well through the tree.
- Pollen is immediately carried away instead of getting trapped on leaves.
- Additionally, spring is a season where winds traditionally blow more than during other periods of the year.
Note that the male katsura cannot bear fruit pods.
If something strange appears, it’s either a female tree bearing pods, or a (rare) type of plant gall.
Long-lasting petals and young seed pods
On a male tree, after the blooming, petals remain attached and help protect young leaves.
On a female tree, the petals fall off as clumps of pods start to form.
Seeds of the katsura tree
Pods contain from 2 to 4 winged seeds. The germination rate of katsura seeds is highest when the ripe pods burst open.
- Learn how to sow katsura from seeds
Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
First female flower (magnificum) by Sten Porse under © CC BY-SA 3.0
Second female flower (japonicum) by Sten Porse under © CC BY-SA 3.0
Male flower (magnificum) by Sten Porse under © CC BY-SA 3.0
Leftover petals by Danny Schissler for the Plant Image Library under © CC BY-SA 2.0