That would be the young growth in the center of the bush: buds, tiny zukes, stems and even leaves. By chance I discovered that in southern Italy, the edible part of a zucchini plant is more than what you buy at the market.
One of the 8 zucchini plants was looking stressed and upon inspection the whole thing lifted right out of the ground with zero root system attached. An empty hole with a tunnel leading downwards marked the spot where the zucchini had once flourished. Field mice arm yourselves (for I am certain that it isn't the work of moles), you're about to engage in battle.
I'd say I was more than a little peeved at finding this but when I saw that a little frugality never hurt if you don't mind a little work, the first thing I wanted to do was to salvage enough of the plant for dinner. Apparently nothing goes to waste for southern italian farmers, and the blog Sud Italia in Cucina proves this point in a very interesting demonstration on what to do with an excess of plants. The young tender leaves, stalks, unopened buds and young unfertilized female fruit go straight into a vegetable dish fragrant with onions and tomatoes. The stalks are cut into segments and the fibrous outer strings pulled off, like de-stringing beans.
I sauteed thinly sliced onions, some minced garlic and 1 finely chopped hot chile pepper in a small amount of olive oil. Add a spoonful or two of chunky tomato sauce and the prepped zucchini bits and pieces. Cook on medium flame until the stems and leaves have softened (add a bit of water or white wine if the mixture dries out too much). Season to taste with salt and pepper. I added this to egg tagliatelle, sprinkled some grated pecorino on top and it was delicious!