I've two plants with distinctive flowers which most of us would call ''marigolds''. A shorter one with a medium sized double flower has broader leaflets than a taller one with a smaller simpler flowers.

Is this variation between strains typical?

T. erecta have quite huge flower heads, mostly completely filled/ double, and are somewhat taller. The more natural types grow easily 2-3 feet tall.
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You have probably some cultivar of Tagetes patula. The modern cultivars tend to be compact about 8 to 10 inches, with single, semi-double or double flowers. Heritage types grow 3 feet and taller.

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not so common and somewhat more subtle is Tagetes tenuifolia. Its flowers are much smaller and single, the foliage much thinner/more narrow.

so if your Marygolds look quite different, perhaps you got a T tenuifoia and T patula, if not probably just 2 different T patula-cultivars.

Well then, have fun with your Marygolds, bye, Lin

Tangetes tend to be single flowered and come in any height from the taller ones like you have to the mini flowered 8 inch tall plants.

Then there is carnation flowered French marigolds which are double flowered and

the large flowered African marigold.

There are crested marigolds which are a cross between the carnation flowered and the tangetes

My favorite marigolds are the carnation flowered Janie--10 inches tall and Antigua, a 12-14 inch tall African marigold with large 2 1/2 inch flowers

==>> is the question .. more along the lines of these words:

are there significant variation in varietals within a given family ...

if so ... the answer is yes ...

a given set of seeds.. is a function of the breeding that got you to the ultimate plant ...

and with any biological process... there is always throw backs [and we arent discussing species here ...] in the genetic material ....

what always amazed me.. is thinking about some producer producing a million little seed packs for retail sale.. and contemplating how they isolated mom and dad.. and relied on them to have marigold sex.. to the extent that they came up will 10 million little seeds.. and 99.9% of them .. come true from the packet ... according to what you planted ...

so the fact.. that you may have planted one pack of seed and came up with two differing plants.. does not surprise me.. as much as the rest all came out as was predicted...

there is always that weird cousin .. who is a little off.. and the family accepts them.. but doesnt talk about it .. lol .. marigolds though.. are horrible gossips ... lol ...

ken

ps: and if you had them in the same spot last year.. perhaps this was a rogue seedling from last year procreation

I much prefer the taller one with the smaller single flowers for no particular reason I can iterate.

Thanks.