One of the most beautiful vegetables ever, the broccolo romanesco has been cultivated in Italy since the 1500s. It's the only edible plant I can think of offhand that sports a fractal design--meaning that each part is made up of smaller versions of the overall shape, repeating with each subsequent part, down to the infinitesimal. To be accurate, it's only an approximate fractal, since it doesn't go on forever, but stops at the point where it becomes too small to replicate. No matter how you slice it (no pun intended), it's one gorgeous eye-popping vegetable, and a fairly cogent argument for both intelligent design and evolution.
To answer the other question, it's not only edible, but combines the best attributes of cauliflower and broccoli--with a flavor more to the broccoli side (hence the Italian name), but creamier, and without that slight bitter edge. It can be prepared in all the ways you might enjoy cauliflower--steamed, gratinéed, à la Grecque, and in other ways, such as purees and cream soups, in which the original shape is no longer visible. I like to separate the florets and keep their fractal pattern intact, to provide visual interest--let's face it: the main appeal of this vegetable is the outrageous shape!
First, I separated the florets, blanched them in boiling salted water, drained them, and then immediately plunged them in ice water. I spread them out to air-dry while I prepared the other ingredients: roasted and peeled red pepper, fennel bulb, preserved lemon, spicy green olives (pitted), and a little red Swiss chard--all cut into 1/4-inch dice; 2 small shallots, thinly sliced; and a simple vinaigrette made with sherry vinegar, Dijon mustard, freshly ground mixed peppercorns (black, white, green and pink), Celtic salt, and "Old Grove" Greek EVOO. When everything was ready, I tossed it all together in a large bowl.
To serve, I spread a generous bed of very fresh mixed microgreens--radish, bok choy, onion, buckwheat, and arugula--on each plate. I mounded the romanesco mix in the center, surrounded it with cubes of ripe avocado, and drizzled a little of the leftover vinaigrette in a circle over the greens.
The result was an explosion of textures and flavors that oddly enough complemented one another nicely. Those thin green things that look like stems are the onion microgreens, which pack a distinctly pungent allium punch--just one note in this little riot of sensations. In a single bite, you might have a bit of Morocco, a dash of Provence, some Italian smatterings, a vague Greek hint, a stout Mesoamerican presence (the avocado), and that potent tangle of infant greens, each with its own distinct character. You almost forget that this was all about that weird-looking vegetable you decided to bring home.