I will try to upload a photo I took of a 1 year old crown and root system after I had very carefully coerced it from the ground. It used to be here but I have had to re-organize the content of my hosting account. For now, all I can do is describe it.
Imagine, if you will, the face sucker critter from Aliens. Now, imagine that the tentacles of the face sucker are but a mere couple inches below the soil surface and reach in every direction.
This one year old plant produced nearly 2 dozen "fingers" in every direction (starburst pattern) and had, in one year, reached 4 foot from west tip to east tip, north tip to south tip. Some fingerlings reached straight down but that growth was mostly a feathery mesh of rootlets.
The thing about this plant is that "sprouts" form and grow in every direction. Those that find daylight become the vines we lovingly tend to. Those that do not become additions to the starburst mess of oversized spaghetti we refer to as the root system of rhisomes. the actual crown itself consists of a single largish node or knuckle entwined in a ball of root growth.
I know, pictures are worth a thousand words and prior to having pulled this crown I too was unable to entirely picture what the plant was becoming. Maybe I still have that photo. If I do, I will post it again.