I am trying to sort out which entry to use for my recently planted California hazelnut: Corylus cornula var. California or Corylus cornula subsp. Californica, or are these perhaps duplicates. There wasn't a lot of info on either, and I'll try to flesh it out when I figure out which one to use. Thanks.

According to the CoL, Corylus cornuta subsp. californica is the accepted name with C. cornuta var. californica being a synonym.

I see our database has both listed:
Corylus cornuta subsp. californica

Thanks, I will propose that they be merged.

Hi there, I'm looking into planting some California Hazelnut and wondered if you have any updates to speak of? I'm in zone 10a (formerly 8b) and still need to find a source, but wondering about my odds for it doing well. Any info appreciated, thanks!

@Sagery, your question would be better suited for the Ask A Question forum, with many more members perhaps being able to assist, (link found at the very bottom of any page), rather than in the Plant Database forum, since it's a question about the plant and sourcing and not about a database entry.