Katsura tree – is your tree male or female?

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Before a single leaf unfurls, katsura (Cercidiphyllum) opens tiny flowers straight from its buds: pale-red on male trees, with stamens dangling an inch from the branch, white-green and half-hidden on females, their twirly styles reaching out like tentacles. Read them right and you know which tree will set winged seed pods, and which one needs a partner nearby.

The key is to look at the flowers. Male katsura 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.

Examples of other trees that are dioecious include yew, yaupon, poplar, maple, juniper and many more. In the fruit tree realm, a good example is the kiwi tree.

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.

Male or female katsura at a glance

Everything you need is on the flowers, and later on what follows them. Here are the clues side by side, so you can settle the question in a single look at the tree.

Both Cercidiphyllum species flower almost identically, so the same clues work whichever one you grow.

Female katsura trees

Ladies first! The flowers on a female Cercidiphyllum are very small. Like their male counterparts, they emerge from the same buds that will later produce leaves.

• 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

Male flowers aim to spread pollen out as far as can be. That’s why it has pollen-bearing sacs called “stamens” that hang an inch (2-3 cm) out from the branch.

• 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

Petals remain on the branch for a long time, even after the stamens have fallen off. This helps determine whether the tree is female or male, too.

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