Do European and American elderberries cross-pollinate?

I have 4 varieties of American elderberry (S. canadensis) that I started from cuttings this spring, and someone in my community was selling inexpensive potted European elderberries (S. nigra) today, that she had started from cuttings of a named variety. So of course I am buying one. :)

My understanding is that both species will self-pollinate but will produce better with another variety available to pollinate. In the long run I want to collect as many varieties as possible, in order to have as much genetic adaptation potential as possible in my plantings. In the meantime, does anyone know if the American elderberry can pollinate the European one? I am not worried about pollination of the American species as I have 4 varieties that can pollinate each other.

When I tried googling for info on this, I did find one variety that is apparently a hybrid of the two so it must happen, I just don't know if that was a one-off or if it is common.

In my experience here in Texas, the Europeans bloom much earlier--what little they bloom.  So they would not cross pollinate in that case.  (The American varieties sucker, grow, bloom, and fruit exuberantly, however.).  I would guess that the hybrid variety you saw was created though the labors of a dedicated plant breeder, but that's just a guess.

In a quick flip thru John Moody's "The Elderberry Book", I didn't see that he specifically addressed European-American cross-pollination.  He says that they will produce better with a pollinator, but also says that the self-fertility "of some varieties" is debated.  He footnotes that comment with a link to an article that says people studied isolated plants that consistently produce fruit, but it doesn't say whether those were American, European or both.   The link didn't work for me, but I think it is this article, which looks worth a read.  The midwest-elderberry.coop site looks very rich with info.

Academics, aside, it is surely worth a try growing it.  If the Europeans grow well where you are, then at the least you can enjoy the flowers.  I've never tried harvesting my elderflowers, but I do like elderflower products.  Or leave them for the polinators.  Good luck, Andrea!!

Thanks Kerry. Yes, I also had wondered if that plant advertised as a hybrid was developed as a result of plant breeding rather than as a naturally occurring hybrid. If the flowering times are that different, then hmmm, I agree cross pollination is unlikely. I may just have to get some more European elderberry plants of another variety. And we do want to harvest elderflowers so either way it's a win. We are harvesting elderflowers off some of the American elderberries I planted as cuttings in the spring, so that they put their energy into growth rather than fruit this year. It's insane that little sticks I planted two or three months ago are trying to set fruit!

A thread exists somewhere on here that talks at length about elderberry,  and someone said that yes indeed they will cross. Ill try to find it at some point. Bloom time would be my concern as well though

There is a variety called “Marge” that is supposed to be a cross (open pollinated in Marge’s backyard) between European and American elderberry.

From google-
‘Marge’ is a hybrid between the American Sambucus canadensis and the European Sambucus nigra which gives us an elderberry plant with all the characteristics of the European varieties but free from the diseases that plague so many. The berries are larger than the American varieties and ‘Marge’ is also self-pollinating so only one plant is necessary for fruit production. Flowers form on last year’s woody growth, so fruit will form the second year after planting.”

This link here goes into some detail about the different varieties and it does talk about Marge. It does not explicitly say that it is a cross between European and American varieties- it just says one parent is European and the other is unknown.

http://extension.missouri.edu/greene/documents/Shared_Documents/SWregion/Byers/ElderberryPresentationMN.pdf

I just bought a Marge, a Bob Gordon and a Korsor. Does anyone know how they will work with each other? Will I need something else to cross-pollinate with the Korsor?
Thanks!

I'm pretty sure that European and American elderberries are now considered to be the same species, with the American now listed as a subspecies of the European....Sambucus nigra ssp. canadensis.
USDA Plant Profile for American Elderberry

Edit:  Forgot to mention, I also see the Blue Elderberry listed as the same species, Sambucus nigra ssp. cerulea.  So it seems that interesting breeding can occur between these 3 groups.