Heirloom by decent, bred from heirlooms, and kept to the standard of the term. Its gene pool is derived from 4 heirloom varieties that were stabilized in the 1970’s by renowned breeder Tom Wagner. It still shows a potato leaf from time to time. delicious, beautiful, and drought tolerant. Much better than Mr. Stripey. The green flesh is amazing! “Stinkbugs” are less damaging to Green Zebra than most other varieties. at least 10 seeds per packet.