What you see: A large, knob-like protrusion on your apple. It’s woody, corky or rough. The flesh underneath it looks perfectly fine.
What it is: Probably a scar from when the apple was a tiny fruitlet; the scarred area expanded and distorted as the apple grew.
Eat or toss: Eat! The texture of that woody area might not be the best, but the apple is fine, and the area just below the skin should be fine too.
Once upon a time, this apple was a tiny drop of a fruit, ready to grow at the end of an apple tree branch.
We’ll never know exactly what happened to it, but most likely, it was visited by a caterpillar. A very hungry caterpillar that helped itself to a nibble and went on its way.
The poor baby apple was hurt.
The baby apple patched up the injury, using a specialized plant material known as lignin. Lignin also helps trees stand tall. It’s tough stuff.
But the lignified tissue healing the wound was so tough and rigid, it couldn’t grow with the rest of the apple. So as the apple expanded and plumped, the woody bandage distorted and bulged and the apple may have needed to make additional repairs. (The apple might enjoy talking with these avocados, which grew under similar circumstances.)
Ultimately, that left us with a sizable knob-like protrusion on the side of the apple.
The skin there might be tough, but underneath it’s just regular, crunchy apple flesh.
So, the apple looked a little different, but was totally fine! And also delicious.
Thanks to Anna Wallis, Fruit IPM Coordinator for New York State Integrated Pest Management (Cornell AgriTech. Cornell University) for helping me understand what was happening here!
ADDITIONAL SOURCES:
- Lifecycle of an Apple, From Bud to Blossom to Fruit. Darren Turpin. Orchard Notes. March 28, 2023. Accessed March 2025.
- How Lignin Helped Trees Grow Up: A new book details how lignin once protected algae from UV radiation, then later in evolutionary time became a structural support for trees. Riley Black. Book excerpt via Science Friday, posted on March 7, 2025. Accessed March 2025.
