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R. davidii

Posted: Mon Apr 22, 2019 10:17 pm
by jbergeson
I made a trip out to the muddy field with the intention of checking on my R. davidii out there after this tough winter.

(Well, actually it was a very easy winter for crown hardiness due to deep snow cover, but we had some extreme cold in the -35F range that made it a solidly Zone 3 winter up three feet in the air.)

It was really interesting to see this plant pushing buds at the very, very tips of wispy thin stems.

I'm always pessimistic about proper ID, and I'm wondering if anyone has any insight based on the pics.

I purchased this rose from Forest Farm in either fall 2014 or spring 2015.

Unfortunately I can't remember if the hips were bottle-shaped as is shown on HMF. It's possible that they were but I don't think they were held in pendulous clusters as the illustrations on HMF show. HMF says it's a tetraploid, but this plant sure looks diploid in the same way that my R. acicularis from Lawyer look like diploids...very thin stems and relatively small leaves.

Whatever this rose is, if it stays healthy I might use it in breeding for a jolt of hardiness. Hoping it's actually a diploid. Unfortunately the petals seem thin and short-lived, which is a weakness.

Re: R. davidii

Posted: Thu Apr 25, 2019 2:39 pm
by tsilvers
Joe, that's the same davidii I've been working with (from ForestFarm). I'd gotten one many years ago and then got a replacement for it that I've had now for 3 or 4 years. It's almost the size of yours now. I like the yellow and red tinted stems. We never have dieback on it at all, but then again we're zone 6-ish.
I've been wondering about the true ploidy of it as well. My F1 rugosa X davidii is very fertile and davidii x virginiana has only set a single seed from thousands of open-pollinated flowers. I've been wondering if maybe this davidii could possibly be a hexaploid to better explain the fertilities of these two F1 hybrids but I guess being diploid would also explain it.
In any case, I'm enjoying working with it and have some unbloomed seedlings from the F1 rugosa x davidii pollen used on 'Lemon Splash' and 'Cal Poly'. I'm expecting to recover a few repeat bloomers in the next generation [crossing my fingers].

Re: R. davidii

Posted: Thu Apr 25, 2019 3:37 pm
by jbergeson
Thanks for the response, Tom!

Whatever this plant is, I think it could almost be considered Zone 2 hardy.

We should cross it with Therese Bugnet to reinforce interesting stem color.

Re: R. davidii

Posted: Fri Apr 26, 2019 9:43 am
by Don
Do either of you have pics of the flowers?

Re: R. davidii

Posted: Fri Apr 26, 2019 5:41 pm
by Warren
Joe that is not R.davidii it looks all wrong, the blooms should be mid pink with thick petals which last well.
Cheers Warren

Re: R. davidii

Posted: Fri Apr 26, 2019 8:46 pm
by Don
Warren, does it look like Virginiana to you?

Re: R. davidii

Posted: Fri Apr 26, 2019 8:48 pm
by MidAtlas
Where I work, I had ordered a plant of R. davidii from a nursery (not Forestfarm, but another Pacific NW nursery, so there's a good chance these are the same clone), and determined soon after receipt that it was misidentified. I tentatively determined the plant as R. virginiana, but have not taken a close look in a number of years to see if I would still agree with that conclusion.


Re: R. davidii

Posted: Sat Apr 27, 2019 12:19 am
by Karl K
Rosa davidii is reportedly closely allied to R. macrophylla. In fact, it has even been regarded as a variety of that species.

Here is a characteristic that should distinguish the two: exserted styles.

Rosa davidi Crép.
Bull. Soc. Roy. Bot. Belgique xiii. (1874) 253.
Si les styles sont normalement saillants, si leur exsertion n'est pas un accident dû à l'une ou l'autre cause, on peut ranger cette forme parmi les Synstylées.
If the styles are normally projecting, if their exsertion is not an accident due to one or another cause, one can arrange this form among the Synstylae. ... 9/mode/1up

Exserted styles and rimmed pendulous hips (among other traits), explain why Hurst diagnosed R. davidii as AAEE. The salient characters of the species might be assembled by crossing R. macrophylla and R. multiflora, for example.

Re: R. davidii

Posted: Sat Apr 27, 2019 1:18 pm
by jbergeson
The blossoms on this plant are small with thin, short-lived petals. I think there is a good chance it has been misidentified.

It is not similar to my supposed R. virginiana, which are in turn nearly indistinguishable from R. carolina (both of those two came from Lawyer Nurseries).

It is actually closest to my R. acicularis (from Lawyer), which have thin wispy stems and appear to be diploid. Very different from Robert Erskine's Aurora, which was supposedly a selection of acicularis.

Re: R. davidii

Posted: Sat Apr 27, 2019 4:31 pm
by Karl K
jbergeson wrote:
Sat Apr 27, 2019 1:18 pm
It is not similar to my supposed R. virginiana, which are in turn nearly indistinguishable from R. carolina (both of those two came from Lawyer Nurseries).
Erlanson (1934) published a key to American roses.

R. virginiana: Stems stout, much branched. Suckers few, rarely flowering in first season. Leaflets firm and elliptic. Bristles at base and on new shoots, prickles flattened or absent. Teeth 9-30 (av. 14). Stamens 120-155. Newfoundland to eastern Pennsylvania. [stamens ave. 140]*

R. carolina: Stems usually slender, often bristly to tips, if stout usually simple; often decumbent or bending after first season. Prickles, if present, usually terete. Many suckers which often flower with terminal corymbs after main flowering period. Highly variable and "weedy" species. Leaflets mostly 7, highly varied in shape and texture. Teeth coarse, 5-21, av. 12. Stamens 65-130, av. 105. Hypanthium glandular of smooth.

Re: R. davidii

Posted: Sun Apr 28, 2019 1:43 am
by rikuhelin
My R. carolinas are 2 to 3 times taller than my R. virginianas and canes tall and thin (5ft max so far). Latter more bushy and squat like K excerpts (2 to 3 feet). As labelled by Cornhill - vary from 3 to 5 years old. No mistaking them on height form and bloom size criteria in a side by size comparison in my garden if given only 2 possible solutions to the ID equation.

Re: R. davidii

Posted: Sun Apr 28, 2019 9:16 pm
by Karl K
I have to make a correction to Erlanson's 1934 key to Rosa carolina. She wrote, "Prickles, if present, usually terete." This agree's with Michaux's "acicularibus" (having acicles).
However, she neglected to mention the paired, hooked/curved infrastipular prickles. Michaux wrote, "aculeis stipularibus binis".

Re: R. davidii

Posted: Sun Apr 28, 2019 11:56 pm
by Jwindha
I have the same “davidii” from Forest Farm and it is definitely not R. virginiana.

Re: R. davidii

Posted: Mon Apr 29, 2019 1:17 am
by Karl K ... =242417152

The majority of plants determined as Rosa virginiana from the Allegheny and Appalachian mountains (for example, in West Virginia) and from the Midwest (for example, Indiana) are R. carolina subsp. subserrulata. In the eastern United States, putative hybrids and their introgressants with R. carolina subsp. carolina occur from Massachusetts to New Jersey and, rarely, south or north of these states. These are the nothospecies R. ×novae-angliae W. H. Lewis.

Re: R. davidii

Posted: Mon Apr 29, 2019 6:24 am
by tsilvers
Here's an old picture I found of the first plant I had years ago. The new one looks very similar. Both were from Forest FArm Nursery. I don't know what species this really is, if not davidii, but it sure doesn't look like any virginiana or carolina that I've seen.
I'll try to get some better bloom pictures this season.

Re: R. davidii

Posted: Mon Apr 29, 2019 6:31 am
by tsilvers
Oh and I forgot to mention, the hips definitely don't look like the ones on HelpMeFind.
They're not so elongated but more rounded. But they also don't look like virginiana or carolina hips I've seen.
I'll try to get pictures of those this season too.

Re: R. davidii

Posted: Mon Apr 29, 2019 6:35 am
by tsilvers
found another old picture of the rose purchased as davidii from ForestFarm
whatever it is, I've been enjoying working with it! :)

Re: R. davidii

Posted: Tue Apr 30, 2019 1:41 am
by MidAtlas
R. davurica might be a closer match to this FF material. I would agree that these growing season photos don't look much like any of the North American species.

Re: R. davidii

Posted: Tue Apr 30, 2019 5:07 pm
by jbergeson
Thanks, MidAtlas, for the alternate idea.

One of the commenters on HMF said this:

"Rosa marretii, and Rosa amblyotis are the two synonyms of this rose. The species is a member of the Cinnamomeae and closely allied to Rosa Cinnamomeae its self. This species is one of the parents of parents of Thérèse Bugnet."

Which might explain why both this rose and Therese Bugnet have colored stems. However, none of the roses pictured under R. davurica on HMF have that highly upright, wispy habit.

Is yours pretty healthy, there, Tom?

I take all species denotations with a grain of would be more accurate to say "my" R. davidii and "my" R. carolina.

Re: R. davidii

Posted: Mon May 06, 2019 1:06 pm
by tsilvers
Yes, thanks MidAtlas/Stefan!
I looked at the davurica pictures on HelpMeFind and elsewhere and I agree, it definitely looks closer to the plant some of us are growing labeled as davidii.

And it's pretty healthy here too, Joe, whatever it actually is.
Everything is healthy this time of year, but it's usually pretty clean later in the summer too.
Here's how it currently looks here in Maryland.