Your identification points will work in general.

I'm not following your text on the blue-green dust. Do you mean you are seeing the bluish color on plants that are not black raspberries?

Then just resort to--raspberries are prickly and blackcaps are thorny--for identifications.

But then my Black Diamond blackberries have prickly green round canes. This can happen because many blackberry varieties are crosses between black and rasp berries.

Totally smooth canes are most likely to be thornless blackberries.

The botanical distinction between raspberry and blackberry is in the fruit. Raspberries leave the core behind when you pull them off. Blackberry cores come off with the fruit. That's what makes the blackcap a black raspberry and not a blackberry. So as far as finding distinctions in vegetative form, well, it's only going to be general, with exceptions.

For instance: you assert that stem roundness is one of the best ways to differentiate rasp from black, but it isn't. The native little wild blackberry, Rubus ursinus, has round stems. That's how we differentiate the native blackberry from runty seedlings of the invasive Himalayan blackberry.

As far as the thorns go, the native blackberry R. ursinus has very fine thorns, almost hair-like, very difficult to pull out without fine tweezers and magnification. So your thorn characteristic doesn't work either.

The blue bloom that you see on black raspberries is common but not always present, as you state. But if you see it, it's most likely a black raspberry. But, someone could come up with a hybrid between a blackcap and a blackberry that might have the bloom while having the fruit characteristics of a blackberry which would make that plant a blackberry, with the bloom. You see what a mess there would be trying to sort blackberries from raspberries, since hybridizing between species makes a combination of vegetative characteristics.

You can certainly identify individual species of native Rubus without flowers or fruit, and you can know which species are considered to be a blackberry or a raspberry.

Thanks you guys, this has been really helpful! I figured the dividing lines between these plants would be fairly grey. It's frustrating, but eventually (hopefully) I'll learn them. My ultimate goal is to be able to pick out the natives vs the non-natives.

So I took some pictures today of some of the wild raspberries and blackberries around my neighborhood. As well as some of my own and my neighbor's planted raspberries. If you can, please see the comments on these images below and let me know what you think (regarding what it is).

FYI, I would embed these images, but they're fairly hi-rez and I don't think flickr allows external linking anyhow (it doesn't work in the preview at least).

For simplicity...
R = Raspberry
RR = red raspberry
BR = Black Raspberry
B = blackberry

#1 - These three pictures are of what I think are BR, growing wild across the street from me. I see this all over capitol hill in Seattle:

a: This is a closeup of the BR, next to a B plant. The B is lower right, the BR is from the upper left. I've rubbed a little bit of the 'dust' from the BR:
http://www.flickr.com/photos/68789281@N08/7359410356/sizes/k/in/photostream/
b All the thin arches in this image are of the same plant (white coating on the stems):
http://www.flickr.com/photos/68789281@N08/7174180005/sizes/k/in/photostream/
c Leaf closeup of the BR:
http://www.flickr.com/photos/68789281@N08/7174177523/sizes/k/in/photostream/

#2 - This is a plant growing in front of my neighbor's house, that seems to be BR (based on thorn size, stem, etc), but doesn't have a grey coating on it at all. Maybe it's too young? Maybe it's really RR or B?
http://www.flickr.com/photos/68789281@N08/7174175915/sizes/k/in/photostream/

#3 - This is a R plant in my neighbor's yard. She planted it a few years ago and swears that it's RR, though she hasn't seen berries on it in a few years. Notice the grey coating on the central branch in the photo... where I've rubbed off a patch. That tells me it's BR, not RR. But, as has been pointed out, this isn't always true.
http://www.flickr.com/photos/68789281@N08/7359439478/sizes/k/in/photostream/

#4 - This is a picture of the R plants I have in my front yard (raspberry poles trained up tall). I got these from two sources... a lady in Everett via craigslist, and a neighbor down the street. I'm pretty sure that one is red, and the other (further away) is black. Both raspberry.
http://www.flickr.com/photos/68789281@N08/7359442548/sizes/k/in/photostream/

Thanks again for the feedback and the help! It is greatly appreciated!

Errr... in #4, I noticed another BR is in the foreground. The redish stems with partial dusting are the ones I think are BR (given to me by a neighbor), while the others are from a lady in Everett.

Not being familiar with Seattle, I looked at Google maps for Capitol Hill. As I suspected, it is not a wild, uncultivated area.

So you are not likely to find any wild or native rubus in that neighborhood, unless someone has transplanted them from the wild or from a native's specialty nursery.

Birds love rubus fruit and scatter seeds every summer via messy eating habits and droppings. What you are seeing around your neighborhood are seedling plants that may be hybrids from many various cultivated varieties of BR, RR, and B.

So you are not learning native vs. cultivated, but urban seedling vs. berries of unknown parentage ("two sources... a lady in Everett via craigslist, and a neighbor down the street"--did they buy named cultivar plants or just let volunteer berries grow in their yard?)
#1, yes, a BR.
#2--not a BR. BR thorns have a slight back-angle and slight curve.
#3--flower buds too robust to be a BR.
#4--I'm not seeing any obvious BRs.

But then you can keep an eye on this year's fruit and see what #s 2-4 actually do.

The best way to propagate a named cultivar is to let it tip-root in the fall into loose or potted soil, sever it from the main plant in the spring and replant it in the ground. That way it is not a seedling and will remain true to type.
Do that with any berry plants in your garden if the fruit is to your liking. The Boysenberry started as an undocumented, chance hybrid, for one example of a well-liked berry.

I'd look at your photos but garden web has some stupid flash thing over your post and I can't highlight your url.

Larry, native plants show up everywhere. Rubus especially grow everywhere birds fly. You can't really believe that there are NO native plants anywhere in Seattle. Even Portland is crawling with native plants. They do not depend on us to plant them.

Mooserider, if you're serious about learning the native Rubus, check out the Burke Herbarium Image Gallery and do a name search for Genus = Rubus.

Here is a link that might be useful: Burke Herbarium at UW

You're right! I believe that "you are not likely to find any wild or native rubus in that neighborhood (Capitol Hill). Not the same as your absolutely stated "NO native plants anywhere in Seattle".

There are likely some native Portland rubus in Forest Park, Sauvie Island, or along the Columbia Slough. But these are not long-standing highly developed urban neighborhoods. I'm not seeing any in decades of extensive running/walking in SE Portland.

Thanks you guys! I'll update with some more photos soon. I'm a newbie, but I hope to be able to identify native from non soon. You're help is beyond helpful, thanks! So many subtleties.

FYI, why is number 3 not a BR? It has a lot of dust on the stem, and no 'beveled' flat surfaces on the stem (i.e., not B).

thanks you guys!!!

Looks like the flower buds in pic#3 are from another plant. Still, cane has more characteristics of a RR, although exceptionally prickly. Blackcap canes, once you are far along the cane, just have the occasional curved thornlet.

You are indeed correct Larry. Those are from something else.... I think that's from that bellflower we get up here that's crazy invasive. The pink/purple and white ones, with the long skinny leaves. Can't remember their names. Maybe not that particular plant, but it's definitely NOT part of the RR/BR that I was pointing out.

Larry, one question: can I not trust the white 'dust' on the canes as being black raspberry? That's what all the sites say.

I'm not sure. I've seen a number of red raspberry patches with bluish/whitish-appearing canes (but not as blue as blackcaps).

I can't grow RR on my lot in the ground--they always die out after a couple of years, so I don't have as much experience with them.

That #3 plant could be some odd hybrid.

Native little wild blackberry often has the same 'white dust' on the new growth as the black raspberries.

Just because 'all the sites' say a species has a particular characteristic doesn't mean that characteristic is going to definitively separate that species from all others. Species descriptions are maddeningly incomplete. And plants are variable.

Hi,

Are there any wild berries that resemble raspberries but that are poisonous? If y'all know I'd really appreciate an answer.

thanks!

marsha

Marsha, where are you?

I don't know of any poisonous berries that resemble raspberries here in the PacNW. Someplace else, maybe, but not here.

Mulberries, can you spot the BRB?