Zucchini and yellow summer squash are varieties of summer squash. Squash has its ancestry in the Americas, but the modern version of zucchini developed in Italy at the end of the seventeenth century. Zucchini that is bitter should not be eaten since the bitter taste signals the presence of toxic bitter substances (Cucurbitacea).
From Wikipedia: “Zucchini or courgette is a summer squash which can reach nearly a meter in length, but is usually harvested immature at 15–25 cm. In the British Isles, a fully grown zucchini is referred to as a marrow.
Along with certain other squashes and pumpkins, it belongs to the species Cucurbita pepo. Zucchini can be dark or light green. A related hybrid, the golden zucchini, is a deep yellow or orange color.
In a culinary context, zucchini is treated as a vegetable; it is usually cooked and presented as a savory dish or accompaniment. Botanically, zucchinis are fruits, a type of botanical berry called a "pepo", being the swollen ovary of the zucchini flower.”
“When used for food, zucchini are usually picked when under 20 cm (8 in) in length, when the seeds are still soft and immature. Mature zucchini can be as large as a baseball bat. The larger ones are often fibrous. A zucchini with the flowers attached is a sign of a truly fresh and immature fruit, and it is especially sought after for its sweeter flavor.
Unlike cucumber, zucchini is usually served cooked. It can be prepared using a variety of cooking techniques, including steamed, boiled, grilled, stuffed and baked, barbecued, fried, or incorporated in other recipes such as soufflés. ...
Zucchini can also be eaten raw, sliced or shredded, in a cold salad, as well as lightly cooked in hot salads, as in Thai or Vietnamese recipes. Mature (larger sized) zucchini are well suited for cooking in breads. Zucchinis can be cut with a spiralizer to make zucchini noodles for low-carbohydrate recipes.”
“Zucchini are low in calories (approximately 17 food calories per 100 g fresh zucchini) and contains useful amounts of folate (24 μg/100 g), potassium (261mg/100 g) and provitamin A (200 IU [10 RAE]/100 g).”
“The female flower is a golden blossom on the end of each emergent zucchini. The male flower grows directly on the stem of the zucchini plant in the leaf axils (where leaf petiole meets stem), on a long stalk, and is slightly smaller than the female. Both flowers are edible and are often used to dress a meal or to garnish the cooked fruit.
... There are a variety of recipes in which the flowers may be deep fried as fritters or tempura (after dipping in a light tempura batter), stuffed, sautéed, baked, or used in soups.”
“Members of the plant family Cucurbitacea, which includes zucchini/marrows, pumpkins and cucumbers, can contain toxins called cucurbitacins. These are chemically classified as steroids; they defend the plants from predators, and have a bitter taste to humans. Cultivated cucurbitaceae are bred for low levels of the toxin and are safe to eat. However, ornamental pumpkins can have high levels of cucurbitacins, and such ornamental plants can cross-fertilize edible cucurbitaceae - any such cross-fertilized seeds used by the gardener for growing food in the following season can therefore potentially produce bitter and toxic fruit. Also, dry weather conditions/irregular watering can stress the plant and favor the production of the toxin. The toxin is not destroyed by cooking. Humans with an impaired sense of taste (particularly among the elderly) should therefore ask a younger person to taste the zucchini for them.
In August 2015, a 79-year-old German man and his wife ate a zucchini grown by a neighbor. The couple noted the unusually bitter taste. Shortly afterwards they were both admitted to Heidenheim hospital, apparently with symptoms of a gastrointestinal infection. The wife, who had eaten a smaller portion, survived, while the man died. Toxicological analysis of the meal confirmed the presence of cucurbitacin. Investigators warned that gardeners should not save their own seeds, as reversion to forms containing more poisonous cucurbitacin might occur.”