Comfrey and Mangoes

Does anyone have experience with growing comfrey with mangoes?

I purchased several root cuttings of Bocking #4 comfrey last October and planted one cutting near the base of every fruit tree I have in my knee-high-to-a-grasshopper food forest. All the cuttings were the same size and most of them grew into nice sized plants. However, the one I planted next to my mango tree has grown to be huge! I didn't know if this was just an overzealous root cutting, or if there is actually some chemistry between the plants. Has anyone else noticed anything similar?

I've attached a few photos to show the size of the different comfrey plants.

I have another mango tree that I plan on planting elsewhere on the property, and I'll see if the comfrey does the same thing. I also can't wait for the weather to warm up to see how much my mango grows this year. YAY experiments!