I study fungi at a big 19th-century cemetery in Brooklyn, going on daily walks to see what's new. It's unusual terrain for the city—hills, meadows (albeit studded with upright stones and obelisks), ponds—because it's terminal moraine, where a glacier ran out of gas. It's also a splendid arboretum—8,000 trees, with many unusual species—and excellent for birdwatching. Nice place to be outdoors and usually not in the least crowded unless you count the true regulars, who number about 600,000 …