I read a question here about zinnia marylandica. I don't know anything about tetraploids but I saved seeds in 2015 from zinnia Zahara Sunburst. These are short branching, xeric and they bloom like crazy all summer long.
The 2016 plants that I grew from those seeds seemed identical to the parent plants. So I saved seeds again this year and will grow them in 2017 since we had such great results.
