A verticiel green roof - 5 years later

It's the end of year 5 of tracking this rooftop. To check out how it has changed over the years, check out last years' look back.

Here's a recent photo:

Some notes from this year...
 
-Did you know after a large chive flower goes to seed, it has about 300 seeds? And a dandelion...about the same amount! How do I know? I actually counted a few on a rooftop!!!
-Moss mats can make an effective weed blocker.
-These festuca grasses can be tricky. One of them I thought was dead. Low and behold, it came back this year and even produced seeds!
-The Sedum spurium "dragon's blood" (from the left of the stone path) and Sedum spurium "tricolor" (on the far right) are slowly overtaking the Sedum angelina (in the middle). Notice how the yellow patches are decreasing each year. They are drooping on top of the angelina, sprouting new plants and growing on top of it. It's difficult to see but the sedum angelina is invading new territory by growing low to the ground and filling in space underneath its' neighbors.
-I need to look up this phenomenon where tree seedlings change colors to blend into their surroundings. I've noticed the maple seedlings will become more red or green based on what the sedum species are doing next to them...regardless of the season.
-You can see the chives are amazing. Slowly, but surely they are popping up in places where they weren't years ago.
-The sedum mat in some places is 2 inches thick.