What you see: A dry line running down the outside of a tomato, with a hole or two in its midst
What it is: A sign that, way back when, a part of the tomato flower got stuck where it shouldn’t have
Eat or toss? Eat! If big enough, the scarred areas may have an unappealing fibrous texture, but they don’t indicate anything is wrong with the rest of the tomato.
There’s nothing like seeing a dark, scarred-over tunnel in your tomato. One so deep that you’re not quite sure you can see where it ends.
But, when you see an arrangement like this, with a scarry hole or two, threaded by a rough line, you can rest assured that it's not a portal to The Upside Down. Rather, it’s a scar the tomato has carried with it, just about ever since it was a flower en route to fruit-dom.
So, the tomato flower did its flower thing, blooming, and making pollen available on a structure shaped like two little rice grains atop skinny stalks in the middle of the blossom. That rice-grain-like structure is known as an anther and is considered to be the “male” part of the flower.
Something weird happened with the flower parts
Meanwhile, below the anthers, somewhere just above where the flower connects to the stem, the “female” part of the flower, the ovary, was gearing up to grow into the tomato fruit that would protect its seeds. For a visual on the ovary and anther arrangement, check out this link (warning: linked content may not be appropriate for some audiences).
In a gape-faced tomato like the one pictured here, you’re probably seeing a spot where the anther and its skinny stalk, or possibly just a petal, somehow stuck to the ovary, creating an injury that started out small in the delicate baby tomato skin but grew and scarred over and hardened as the tomato reached its full size.
A reminder of the scope of impact when the tomato was small, this injury usually goes all the way from the fruit's "stem end" to its "blossom end." The blossom end is the spot where the flower once was, but, once this tomato is resting on our kitchen counter, most of us are going to call it simply "the bottom."
Heirloom tomatoes are more vulnerable
Lots of environmental factors can cause this phenomenon, known as "zippering" (note: zippering is sometimes just a line and not a hole), ranging from cold weather to humid air. Heirloom tomatoes are particularly susceptible.
“That’s a challenge for a lot of growers,” said tomato plant breeder Emily Rose Haga. “People want these colorful heirloom-type tomatoes, but they do respond to their environmental conditions in ways that can cause some abnormal fruit.”
Still safe to eat
And, of course, because these dry holes and lines represent successfully healed wounds, the tomato is still perfectly fine to eat. Just wash as usual, and give that rough part an extra rinse to make sure you've knocked out any dirt that may have accumulated.
Then, just love these holey, scarry, tomatoes and they’ll reward you with lots of heirloomy flavor!
If you’re seeing just a hole, and no associated line, you could be looking at a fruitworm injury. Check out the Missouri Botanical Garden's page about tomato fruit problems for an image of what that might look like.
Emily Rose Haga. Plant Breeder. Tomatoes and Peppers. Johnny's Selected Seeds.
Tomato Fruit Problems. Missouri Botanical Garden.
Tomato plant's male reproductive organs shrivel under high temperatures.
The Lifecycle of a Tomato Plant. Tomatosphere. Let's Talk Science.
Flowering plant life cycles. Science Learning Hub. University of Waikato