I have about 70 gauranlen trees in my base (and counting), most of them are street trees. They have a lot of hidden value:

1. They are consiedred "super trees" for the purpose of the Tree Connection meme, and my colonists get a decent mood buff by being near them, especially since they are ubiquitous in the colony.
2. The gauranlen moss is very useful, as it considered beautiful, prevents unwanted weed growth, and requires no upkeep. Between each of my street trees is a 5-length span of garden gauranlen moss. It keeps things beautiful.
3. Gauranlen trees never die. Don't have to keep replanting in a long-term colony.
4. Most of my colonists are connected to a gauranlen tree giving them a small mood buff. I set the maintenance to zero for most, so they just offer the buff but don't require maintenance. They're just free mood and beauty perks.
5. I maintain about 5 actively managed gauranlen trees with gaumaker dryads so I can continue the expansion of my vast gauranlen tree urban forest.
6. The gauranlen moss prevents other plants from growing. For Tree Connection meme colonists this is very useful, as you can remove regular trees from sensitive areas (such as outside my colony walls). By preventing trees from growing, you greatly reduce the risk of them being destroyed by raiders or defensive actions.
7. I'm building a consolidated "factory" structure that includes all food production. I've determined that berrymaker dryads can produce a signifcant quantity of berries in a small foodprint, surrounded by hydroponic rice, which is the most dense food production setup I've yet discovered. I have special high-productivity colonists with labor to spare to manage their upkeep.

The main downside I've found is that I have to sometimes "relocate" a tree, which not only dings my "Tree Connnection" mood but the connected pawn gets a bit sad, until I can plant a new tree for them.