It is an edible flower bud of the species Brassica oleracea, which also includes regular broccoli and cauliflower.

[2] Romanesco has a nutty flavor and a firmer texture than white cauliflower or broccoli when cooked.

[3][4] Romanesco superficially resembles a cauliflower, but it is chartreuse in color, with the form of a natural fractal.

[6] The causes of its differences in appearance from the normal cauliflower and broccoli have been modeled as an extension of the preinfloresence stage of bud growth.

[7] A 2021 paper has ascribed this phenomenon to perturbations of floral gene networks that causes the development of meristems into flowers to fail, but instead to repeat itself in a self-similar way.