Identifing species

What is the best resource to identify species roses? Is there a key out there somewhere? I have been on helpmefind and pictures and brief descriptions can only go so far? And I would really want to be able to identify the species systematically especially the north American species.

I cannot say which is the “best” but you may find this site useful:

http://www.rogersroses.com/

Link: www.rogersroses.com/

A key for the Eastern North American species was published in the paper by Walter Lewis et al. on Species east of the Rockies. Send me an email if you’d like a copy. I’ve found that keying works best for widely divergent species. For some intergraded species where the ranges of two overlap and/or they hybridize, identification can be frustrating.

I follow this MO with some success locally:

  1. ID the species that exist in that locality. USDA PLANTS shows species by county in some cases.

  2. Rule out the species that don’t match key morphologies and especially hip shape and sepals if not in bloom as well as armature (works better for some species than others). Check for glands and bristles on every surface - canes, peduncle, rachis, leaf surfaces.

  3. Look for keys to local species in local Floras, not in rose resources.

  4. Use Native Plant Society resources. Some Native Plant Societies maintain exhaustive data bases that list plant species by location within a county.

  5. Check local botanical gardens for specimens, but beware of nursery propagated specimens that are chosen exactly because they are atypical.

  6. Open your observational powers to the reality that species can be much more variable than garden roses. Some are hugely variable, while others are instantly identifiable by one or two key characteristics. Anyone can ID Rosa setigera. OTOH about the only way to ID some species with extensive ranges is to rule out everything else.

Here is a good key to the native and naturalized rose species in California:

Link: ucjeps.berkeley.edu/ina/roses/rosa_key.html