The problem is you didn't show the leaves. You should be able to find out what it is from the Garden anyway, botanical gardens are supposed to be telling people what they are displaying. They might have a place on their web site where you can make queries about the collections, or a phone number you can call for information about specific accessions. Looks like this one is prominently situated. What I have seen here with a more or less similar trunk is Cydonia oblonga.

I think the one you have labelled as bunchberry is rue anemone- anemonella thalictroides, i believe. It's def not bunchberry. The thistles were the ones i didn't know- i thought the first one was crimson clover! The fern you don't have labelled looks like lady fern to me, but i'm no expert. The second photo looks like oxeye daisy to me. I'd like to know what the first shot is as i have this wildflower/weed in my garden. And i was tickled to see the ID on the yellow violet.

I also have a horde of Vinca growing happily in the side yard under a large Norway maple. I've removed tons in other parts of the yard to make gardens, mostly via digging and smothering. Digging is hard, smothering is relatively easy. First I scalp it by mowing it down as low as possible, then smother with cardboard topped with layers of organic material (i.e. lasagne gardening or sheet composting). Be sure to overlap the cardboard well or it will grow through. This does indeed kill the Vinca and as the layers decompose it will create a nice rich bed for planting. In defense of Vinca minor, it can be useful in a hard to grow and contained location, and it's attractive. But in my experience it is very aggressive and will choke out pretty much everything except for mature established shrubs and trees, native or not. I also had 5 large Norway maples, but have had 4 of them removed (1 huge one left). Even for a maple, they are particularly difficult to grow underneath, as they cast a dense shade, and have mildly allelopathic roots that will suck all the moisture out of the ground. Some natives that will grow in dry shady or open woodland include White wood aster (Symphyotrichum divaricatum), Blue wood aster (S. cordifolium), White snakeroot (Ageratina altissimum), Woodland sunflower (Helianthus divaricatus), Northern sea oats (Chasmanthium latifolium), Viola, and possibly native Columbine (Aquilegia canadensis). I'm sure there are others. You should conider moving the Juglans nigra as they have very allelopathic roots and are difficult to grow under. They also eventually grow into very large trees with wood that is quite valuable.

Seems I can only up-load one foto of the flower - foto two had the reverse side 'flat' green area. Here is my email address for fotos 2 & 3 which give a more definative view. rogergarlick@optusnet.com.au THANKS ROGER! Here is a link that might be useful: Rogers Rammed Earth