The roots are as stiff and inflexible as the stems. This is only part of one mass that I dug up. The green stems, either angled or rounded, are what you see above ground as small clumps or massive thickets . Older stems become discolored, sort of a dark grayish-brown. The whitish colored stem is typical of the underground portions, which are actually rhizomes.
Any parts totally buried are whitish to ivory in color.
Most of these 'briers' have edible portions and have been used medicinally for centuries. S. rotundifolia roots are rich in starch and can be dried and ground into a powder for use in making cakes, puddings, sweet drinks resembling root beer, jelly or soups. I have read that raw young shoots can be added to salads or cooked like asparagus. If you dig up a rhizome, you will see a swollen section every so often that is used to store food for the plant. Like most plants, continual removal of leaves and above ground stems will eventually kill it, but this one requires more diligence than most because of these underground reserves.