Put the soaked, drained beans in a 5- to 8-quart slow cooker, and season them generously with salt and pepper. Add the Parmesan rinds and the wheat berries.
Warm the oil in a large skillet over medium-high heat. Add the onion, season generously with salt, and cook, stirring occasionally, until softened, about 5 minutes. Add the fennel. Continue to cook, stirring often, until the fennel is softened and the onion is lightly browned, about 5 more minutes. Add the celery and garlic, and cook, stirring, until just softened, about 1 minute. Add the fennel seeds and red pepper, and cook, stirring constantly, until combined and fragrant, about 1 minute. Add the rosemary and the wine and let the wine bubble until the pan is almost dry, about 2 minutes.
Scrape the mixture from the skillet into the slow cooker. Add the stock, and season it: Add ½ teaspoon salt, if you are using low-sodium broth, or 1 teaspoon salt, if using homemade unsalted stock. (Do not add salt now if you are using fully salted broth.) Stir to combine, and cook on low until the wheat berries are tender and the beans are creamy, about 8 to 10 hours. (Taste the beans to make sure they are creamy; they can vary in their cooking time depending on their age.) The soup can hold well on warm for 1 to 2 additional hours.
Before serving, remove and discard the rosemary sprigs. Stir in the parsley, lemon juice, and reserved fennel fronds. Taste and add salt and pepper if necessary. Serve in bowls topped generously with grated Parmesan.

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