Not Petals After All! The Secrets of Japan’s Ayame and Kakitsubata Irises
Hi, I’m Ken Kuwako, your Science Trainer. Every day is an experiment.
“This flower has six petals, right? Well, it turns out they’re not all petals.”
Irises were blooming in my parents’ garden, so I stopped to take a good look. Standing in front of those vivid blue-purple blooms, I found myself wondering, “Which part of this flower is which?” And so I decided to find out.
Is that park flower an ayame or a kakitsubata?
This one was blooming in a park. It might be an ayame.
Ayame, kakitsubata, and hanashobu are all members of the iris family, and they look remarkably alike. They’ve been famously hard to tell apart for centuries, so much so that Japan has a proverb for it: “Izure ayame ka kakitsubata,” meaning “Which is the iris, which is the other iris?” It’s used when two things are so wonderful that you can’t decide between them.
Want to tell them apart? Look at the base of the large drooping parts at the bottom of the flower (the ones that look like outer petals).
・Ayame has a yellow patch with a purple, net-like pattern.
・Kakitsubata has a single whitish (or yellowish) stripe.
・Hanashobu has a yellow stripe.
Where the flower is growing is a good clue, too. Ayame prefer dry grassland, while kakitsubata like waterside spots and wetlands. So why not check the photos and see which one the park flower really is? It’s a fun little detective game.
Let’s check the science handbook…
I looked up ayame in a Rika Binran (science handbook), and it says that in ayame, it’s hard to tell the petals and sepals apart. So what I took for all petals wasn’t quite right after all!
In a typical flower, the sepals sit on the outside and the petals on the inside, and the two look and work quite differently. But in the iris family, sepals and petals are both brightly colored and grow large. The three outer ones hang down, while the three inner ones stand up thin and upright. Look closely, and even though there are six in total, their shapes and sizes are quite different.
Digging a little deeper, I spotted the stamens, and what an interesting design they have! In irises, the tip of the pistil splits into three and spreads out into petal-like shapes. The stamens are tucked away underneath those spread-out parts. And there’s thought to be a very good reason for that.
Picture a bee arriving in search of nectar. It lands on one of the big drooping parts, then wriggles inside, and the pollen from the stamen lands right on its back. When the bee crawls into the next flower, that pollen rubs off onto the pistil. In other words, those big, showy parts work as a “landing pad” and a “runway” that guide the bee straight to the pollen. The shape of a flower is packed with clever tricks for teaming up with insects.
References
・How to tell ayame, kakitsubata, and hanashobu apart, and where they grow (Rika Binran)
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