I have watched these old roots grow for over 30 years. They all don't come up every year. they some times lay dormant for two to 3 years. Every now and then I get a supprise and one I have never seen before shows up. On an average year there are 6 to 8 big 4 prong plants that make it to berry stage. and we always plant them as soon as they get ripe. I don't think that the big old ones do come up every year.
strange things happen i have a spot that i planted about 5 years ago the next year they came up looked good then mother nature gave up a nice ice storm and all the tree tops came down and the spot got full sun. i thought the plants died when none came up and it stayed sunny in that spot for the last few years but this year i walked thru the area and under the weeds were my plants some that got good shade came up as big 3 prong and some are small 3 prongs some even had seeds this year .