This is something you should probably file under "Don't Do This At Home". *laughs*
When you manage a large collection of roses, especially one in which new seedlings are generated by the thousands every year (for 13 years!), you are inclined to let certain housekeeping chores slip. Case in point is what you see happening in the photo here. Years ago, I shoved a seedling flat under a bench after I had potted up the seedlings in it. (The red arrow in the lower left points at the outline of the flat) Every year a small percentage of seeds germinate much later than their flat-mates, often not until the Fall or the following Spring. Such was the case here: the flat lay under the bench, undisturbed, and here we are 6 or 7 years later with late germinating seedlings well rooted into the soil below the flat, and sending up vigorous canes through the metal grid bench tops! Three times now I have hacked these seedlings down to stumps, and this is how they look this weekend: happy and rarin' to go. As it happens, one of these is a seedling that hasn't yet flowered: a cross of ("Lemon D" X 'Scarlet Moss') X 'Fakir's Delight', all of which are complex Moss hybrids from Ralph Moore's library of inventive crosses. So, I don't dig these out because I am waiting to see this last, late seedling bloom.
At the far left side of the frame you see a hint of another seedling that escaped its flat entirely. It reaches to the roof of the house now and is wickedly thorny, although as is often the case with roses of modern Moss pedigree, the thorns are not particularly sharp and it would take some effort to actually injure yourself on them. I have documented the left-most seedling in previous posts, labeling it as simply "Floor Moss". Click the link to see a photo. I'm using "Floor Moss" in breeding now, since it tends to be very clean and has great vigor. Oh yeah, and the blooms ain't bad either.