I’ve heard a lot about “heirloom” tomatoes. I understand their appeal having tasted a few varieties, but I wonder, what exactly qualifies a tomato as “heirloom”? —AM, Mass.
Answer: Any open-pollinated tomato that was inexistence before 1940 when the first hybrids were marketed is considered an heirloom. Open pollinated means that saved seeds will produce a tomato identical to the parent plant. Dr. Craig LeHoullier and Dr. Carolyn Male, both heirloom tomato experts, have further divided heirloom tomatoes as follows.
Class I: Open-pollinated varieties that were in existence before 1940 and were handed down from generation to generation by families, ethnic enclaves, and regional farmers. They may never have been available commercially, or if they were, their real names have been forgotten and replaced by family-oriented ones, according to LeHoullier. Varieties like 'Aunt Ruby's German Green', 'Anna Russian' and 'Cherokee Purple' belong to this class.
Class I I : Open-pollinated varieties in existence before 1940 that were developed by seed companies and used by farmers and gardeners. Most of them went out of favor commercially when hybrids appeared. Examples are 'Abraham Lincoln', 'Luther Burbank' and 'Paragon'.
Class III: The open-pollinated descendants that result from the cross breeding of two heirlooms are considered by some experts to be legitimate heirloom varieties, too. Purists such as LeHoullier and Male don't recognize them as such, but several seed catalogs list tomatoes in this class as heirlooms. 'Green Zebra', 'Banana Legs' and 'Fireball' are members of this group.