Neighbors, please don’t call animal control. The Battery Rooftop Gardener’s determination to push the boundaries of green roofs has not turned in a zoological direction. “Green Zebra” is a variety of tomato (Solanum lycopersicum) which, according to Seed Savers, was bred by Thomas Wagner of Tater Mater Seeds and introduced in 1983:
Wager is a potato and tomato breeder from Everett, Washington who reportedly hybridized “Green Zebra” using four varieties of heirloom tomatoes, including “Evergreen,” a medium-size green tomato. Seed Savers describes it as having olive yellow 1½ – 2½” fruits with deep green zebra stripes, although I have never seen the olive yellow color. Mine are green.
The sometimes-reliable web reports that Alice Waters was responsible for popularizing “Green Zebra” by using it at Chez Panisse. Perhaps. What I do know is that it does offer a remarkable dialectic of sweet and sour; with the earlier harvest tending toward the tart side, and later harvest emphasizing the sweet.
To be frank, I have had trouble determining when my “Green Zebras” are ready for harvest. Two days ago, half of the tomatoes on my plate were inedible. Today’s crop were picked last night by Melissa Metrick and were all perfectly ripe. The secret, I believe, is to harvest by feel, seeking a slight “give” to the fruit and looking for the light green stripes to begin blushing yellow.
The pedant in me cannot resist a slight digression into question of whether “Green Zebra” should be considered an heirloom variety. At first blush, as a variety bred in 1983, it would appear not. But, not surprisingly, the matter is more complicated. The best explanation of the meaning of “heirloom” in tomatoland comes from a chemist in North Carolina named Craig LeHoullier and a retired professor named Carolyn J. Male, who raises more than a 1,000 heirloom varieties in upstate New York. They have classified heirlooms into the following four categories:
- Commercial Heirlooms: Open-pollinated varieties introduced before 1940, or tomato varieties more than 50 years in circulation.
- Family Heirlooms: Seeds that have been passed down for several generations through a family.
- Created Heirlooms: Crossing two known parents (either two heirlooms or an heirloom and a hybrid) and dehybridizing the resulting seeds for however many years/generations it takes to eliminate the undesirable characteristics and stabilize the desired characteristics, perhaps as many as 8 years or more.
- Mystery Heirlooms: Varieties that are a product of natural cross-pollination of other heirloom varieties.
The experts helpfully note that while all varieties considered “heirloom” are open-pollinated, not all open-pollinated varieties are considered “heirloom.” So, is “Green Zebra” now a “created heirloom”? Perhaps one of my readers will enlighten me.
In the mean time, I can reliably report that – heirloom or not — they make a fine breakfast.