Given that the curly leaf is a mutation of the wild flat leaf species it’s not unlikely that it will throw the occasional reversion.

These reversions seem stem-specific. That is, everything on this particular stem is flat-leaf. It is true that reversions tend to throw back to a more genetically stable variety. I guess the flat leaf is such.

Do these stems with stem-specific leaves go all the way into the ground?

tj

I see something similar with Black Seeded Simpson lettuce. Smooth leafs occasionally in with mostly crinkled leafs. I don't know if both are on the same plant.

Parsley stems don't go all the way into the ground. They fan out at the base. I have three large curly plants in a large container, and three of the perhaps twenty stems on this one plant have flat leaves. I know of reversion mainly from variegation on plants, which is unexpected color patterns on the leaves. But this is different.

When my curly parsley goes to seed, the bolting stems have flat leaves, which then become elongated and flat. Is it possible your plant is in that moment just as it bolts? Has it spent a winter with you already?

Nope. New plants. But that's interesting that a bolting plant tends to revert.

In my area, most commercial parsley plants are actually several clustered plants, all growing inyermingled, and one seed may have been of a different variety if it wasn't a reversion to flat leaves.

As I said, these stems were all coming out of the same plant. Easy to see.

I would love it! Id use the Italianfor cooking and the curley for garnish. As it is, I have one (or more) of each.