It is interesting to note the change in gardening philosophy that keeping bees can bring. In my former gardening life, the spent brassicas wouldn't have been occupying precious barrel space. None-the-less there they were still, all gangly, twisting their long flowering stalks lazily atop the deck, effortlessly attracting entire tribes of aphids. By all rights any self-respecting gardener would have yanked them up by their heads, tossed them to the compost, and made way for something new and more productive.
Enter the bee-minded gardener! Bees and brassicas apparently have coevolved. Bees need brassicas for the obvious nectar and pollen while brassicas need bees to assist in their pollination. They suffer from "self-incompatibility" (don't we all from time to time?): the pollen from one flower will only pollinate the flower of another brassica plant (no inbreeding here). This is a problem for them because their pollen is a bit on the sticky and heavy side and isn't readily windborne. Thus the bees and the brassicas enjoy a symbiotic relationship. Who am I to uproot half of a perfectly compatible partnership?