I have had a bunch of radishes going wild this year that re-seeded from last year. All of them looked the same, with the bulbous root and the lanky stem, the typical leaves, and the white flowers.
Until this came along:
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leaves and flowers and color are all the same as the others, but its stem is about three times the thickness of that of any other radish plant I have. It's so thick it's begun to crack. Is this a mutation? The result of odd pollination? Not a radish at all?