By Harold McGee
In the case of broccoli, extra flower-stalk tissue develops, fuses into thick “spears,” and then goes on to produce clusters of small green flower buds. In cauliflower and its interestingly angular, green variant, romanesco, the stalk-production stage is extended indefinitely and forms a dense mass or “curd” of immature flower-stalk branches. Because the curd is developmentally immature, it remains relatively unfibrous and rich in cell-wall pectins and hemicelluloses, and so can be pureed to a very fine, creamy consistency (and if overcooked whole, it readily turns to mush). To get as white a cauliflower curd as possible, growers usually tie the leaves over it to protect it from sunlight, which induces the production of yellowish pigments.