The local cotton grass is in seed at the moment. It thrives in poor, acidic, boggy soils. Even after it has seeded, its dying, rust-red stalks are easy to spot, warning you of areas best avoided, unless you've brought your wellies.
Because cotton grass thrives in bogs, and bogs mainly tend to form in flat areas (albeit often flat areas high on moors), when the grass comes into seed, you can spot huge, flat swathes of white on the hillsides around here. From a distance, they can look uncannily like limestone pavements:
(Not that we get limestone round here, you understand. That's a different Yorkshire entirely.)