F1 hybrids vs X Hybrids

Asked June 12, 2018, 4:46 PM EDT

Hello, I have heard about F1 hybrids in vegetable plants such as tomatoes. I have also heard about hybrids designated with an "X" between genus and specific epithet, such as Clematis X jackmanii. Are these the same kind of thing? Are F1 hybrids the result of crossing 2 different species, which I believe is what Clematis jackmanii is? Thank you

Philadelphia County Pennsylvania master gardener program plant breeding

3 Responses

Here is a link to an explanation of the botanical naming of subspecies and varieties. F1 hybrids refers to a first generation cross between two parent plants. The cross isn't identified and the seeds won't breed true to the parent. For example, Sun Gold tomatoes are an F1 hybrid. The breeder wants to keep the parents plants unknown. That way new seeds must come from the breeder.

When two botanical species are cross bred with each other and the seedlings (= the cross itself) are described scientifically, then this is a called a hybrid species name. In a hybrid species name there is always a × mark between the genus name and the hybrid species name. The × is not written in italic and always in a small size. This × mark is written against the hybrid species name, so without a space.

Thank you very much, Eileen. Your response is very helpful