I'm sure that there are plenty of factors that contribute to the size of roots. Here is a picture of one that stumped me a little bit. Its hard to tell now that its dried, but this root is 47 years old. What you see is how it came out of the ground- there were no root hairs or any other parts, as it was dug very carefully. About a foot away form this one was a very nice 8 year old root that was very nice size. This small root put up a decent 3 prong plant that had 6 berries ( I wish I would have taken a picture of the top). In close proximity to this plant were a dozen or so other plants all of normal size with respect to age. So ideas as to why this is so small?? Animal damage?