I got the mother plant as a baby from a wild colony of exclusively single-flowered plants growing in a medieval ruin.
It grew up nicely and bloomed single as was to be expected.
The next spring I had some self-set seedlings in pots which i potted up and to my amazement, from the 5 offspring plants I had, 4 where double-bloomed looking like the cultivar Tanacetum parthenium 'Flore-pleno'.
I have never had the double-flowered form..
Maybe not a big deal, but anyhow it find it strange..

Now that is interesting!
Do your neighbours grow the double form?
Or maybe your original was a hybrid of the single and double?

Thanks, no Caroline, my garden is enclosed by tall walls and my neighbours are not gardeners and have no flowers in their garden, and I don't think the mother plant could have been a crossing of the single with the double, I'm really sure there where no doubles growing on that medieval ruin..

Thank you for the !

I've always grown just the doubles. I prefer them.

Perhaps this was a sport? But multiples does seem like a long shot for a sport.

jvdubb said:I've always grown just the doubles. I prefer them.

I am curious, did you ever get a single out from those doubles, that is if you have grown them from your own seed?
The doubles are pretty, agreed, but still I prefer the singles..

I did grow mine from seed. I never noticed any singles. But also, I remove A LOT of them before they bloom. They border on invasive for me. So, I guess it is possible that there was a single or two among them. We'll never know.

Double or single, they are both so pretty.

Very interesting! I grow both in different parts of the garden, and both have only ever produced seedlings like the parents.

Thanks Neal for your report, it makes my story even more odd!

Myriam, do you see a difference in the foliage when comparing the 2? Here one the foliage of one is more divided and lacy than the other, but at the moment I can't recall which is which.

A difference in the foliage didn't call my attention, Neal, they looked all the same to me, though I didn't pay close attention to that. It is difficult to check that out now, as they have stopped blooming since a couple of months, they are all planted in containers, and I don't remember who is in what pot..
But I can find that out next season..I probably will have more seedlings too..