It should be noted that Zucchini in the US is largely genetically modified unless you purchase organic.
Zucchini (aka vegetable marrow, Italian squash) is a fine example of New World foods circuitously introduced to the USA via Europe. In this case, Italy. The word “zucchini” is the Italian diminutive for the word “gourd,” [zucca].
“Zucchini, the Italian and American name for what the French and many English speaking people call courgettes, any of several varieties of squash…which have been developed for this purpose and are still relatively small…when mature. This is one of the most attractive and delicious of the cucurbit vegetable fruits, but only became prominent in the 20th century. In the 1920s, when the learned Dr. Leclerc was writing, the French still referred to courgettes d’Italie, and it seems clear that it was the Italians who first marketed the vegetable marrows in a small size; and that it is therefore appropriate to choose their name zucchini rather than the French name…The 19th-century French author Vilmorin-Andrieux…gave a illustration of the elongated variety of marrow grown in Italy…The English translator added, more than half a century before the hour of the zucchini struck: ‘This should be tried in England.’ Vilmorin, incidentally, had given the Italian name as cocozello di Napoli. That there is no true English name reflects the fact, that, although courgettes were mentioned…in a few English recipe books of the 1930s, they only became popular in England after Elizabeth David in the 1950s and 1960s had introduced them…to readers of her books; and that as zucchini they had a similarly late arrival in the USA, where Italian immigrants made the introduction.”
Oxford Companion to Food, Alan Davidson, second edition edited by Tom Jaine [Oxford University Press:Oxford] 2006
Pellegrino Artusi’s Italian culinary classic Science in the Kitchen and the Art of Eating Well  contains recipes for Zucchini Pie, Zucchini with Meat Filling and Zucchini with Oregano. The book has been recently republished in English by Marsilio in New York.
“Vegetable Marrow: a kind of squash, eaten as a vegetable, which is very popular in England, but is not often seen here. The true English type is, when full grown, generally about nine inches long and four inches in diameter, with green to yellow rind and light-colored flesh. The Italian variety reaches a length of about twenty inches, with mottled, dark-green rind and orange flesh.”
The Grocer’s Encyclopedia, Artemas Ward [National Grocer:Philadelphia PA] 1911
“Italian restaurants are usually to be found in high-class places, with all the surroundings that make for “class.” Ornate, usually with waxed floors for dancing, good orchestras, and skilled European waiters, they cater to the discriminating and serve cosmopolitan fare of the best sort. But one may get Italian specialties, and wise is he who waives his customary steak and potatoes, and instead scans the menu for real fare of sunny Italy. Zucchini, for instance, that Italian squash which Signore Marcel–and others–import especially. It may be served in different styles, but the favorite is when, cut into small, succulent squares, it is breaded and fried in olive oil.”
Select three vegetable marrows about six inches long, peel lightly, cut a piece from one end and remove the seeds. Press closely into the marrows some well seasoned pork sausage, pin the end pieces on with toothpicks, place in a saucepan, dot with butter, add one cupful of meat stock and one teaspoonful of lemon juice, cover the pan tight and set in a moderate oven for two hours or until the marrows are tender, basting often. Lift the marrows to a serving dish, remove the fat from the sauce, add to the sauce one cupful of tomato sauce, boil up once and strain over the marrows.”
Zucchini bread descends from a long line of European sweet vegetable puddings dating back to the Middle Ages. Carrot pudding is one of the oldest examples. Sweet potato pudding/pie followed in the Renaissance. Carrot pudding crossed from vegetable to cake dessert in the 20th century. Sweet potato pie remains on the dinner table. After WWII, zucchini proved prolific in mainstream American home gardens. Which meant? Too much zucchini. Just like leftover Thanksgiving turkey, recipes proliferated. Zucchini bread (portable, easy, healthy, freezer-friendly) to the rescue!
Food historians generally drop zucchini bread squarely in the American 1960s & 70s. It was promoted (as was carrot cake and banana bread) as a *healthy* alternative to standard desserts. Was it actually healthier? It depended upon the amount/type of flour, sweetener and fat used in the recipe. Generally the bread employs fresh zucchini, which argues logically for the healthy case. Like banana bread, zucchini bread is not frosted.
“Zucchini bread. A deliciously moist, full-flavored bread that became popular in the 60s and remains so today. It’s a splendid way to cope with a summer gusher of zucchini because the bread freezes so well.”
American Century CookBook, Jean Anderson [Clarkson Potter:New York] 1997 [NOTE: Includes recipe from the early 1970s.]
“Zucchini bread. This quick bread was full of zucchini, brown sugar, and vegetable oil, all of which were considered good for you in the 1970s.”
Fashionable Food: Seven Decades of Food Fads, Sylvia Lovegren [MacMillan:New York] 1995
Our survey of American newspaper articles published in the 1950s-1970s confirms the popularity of zucchini. Recipes for zucchini bread proliferated in the mid-1970s. One of the earliest (& perhaps most influential) recipes is this gift from James Beard:
“Carl Gohs’ Zucchini Bread
This rather unusual loaf has a very pleasant flavor, a little on the sweet side, and a distinctive texture. The built-in moisture provided by the zucchini makes it a very good keeper. It can be prepared with 1 cup of whole-wheat flour instead of all white flour. [2 loaves]
2 cups granulated sugar
1 cup vegetable oil
2 cups grated, peeled, raw zucchini
3 teaspoons vanilla extract
3 cups all-purpose flour
1 teaspoon salt
1 teaspoon baking soda
1/4 teaspoon double-acting baking powder
3 teaspoons ground cinnamon
1 cup coarsely chopped filberts or walnuts
Beat the eggs until light and foamy. Add the sugar, oil, zucchini, and vanilla and mix lightly but well. Combine the flour, salt, soda, baking powder, and cinnamon and add to the egg-zucchini mixture. Stir until well blended, add nuts, and pour into two 9 X 5 X 3-inch loaf pans. Bake in a preheated 350 degree oven for 1 hour. Cool on a rack.”
Beard on Bread, James A. Beard [Alfred A. Knopf:New York] 1973