Continuing with root vegetables, the rutabaga (or swede as it's known to other English speaking countries) is a close relative of the turnip, actually originating as a cross between the cabbage and the turnip. It was first noticed in the 1620's growing wild in Sweden, but likely originated much earlier in the Russian/Scandinavian region.
Perhaps most interesting (to me at least) is the vegetable's taxonomic history. Three ancestral species of Brassica (rapa, the turnip, nigra, black mustard, and oleracea, cabbage/broccoli/kale/Brussels sprouts/cauliflower) were able to interbreed, creating 3 allotetraploid (having four genomic copies from two different ancestral species) species: juncea (Indian mustard), napus or napobrassica (rutabagas), and carinata (Ethiopian mustard). This hybridization (shown below) is called the Triangle of U after Korean botanist Woo Jang-choon (apparently mistranslated).
While most organisms are diploid (containing two homologous (paired) sets of chromosomes, one from each parent), polyploidy (having more than two sets) is sometimes observed, especially in plants. For instance, seedless watermelons are triploid, kiwifruit and sequoias are hexaploid, and certain strawberries are decaploid. It is estimated that as many as 80% of plant species are polyploid, likely due to the ability of plants to survive the various mechanisms by which polyploidy occurs, such as meiotic failures or fusion of unreduced gametes. In animals, polyploidy is more common among fishes and amphibians, with some frogs having as many as twelve sets of chromosomes.
At any rate, rutabagas are cooked in many ways, from being roasted with meats to baked in casseroles or boiled in soups. They are also often mashed or pureéd, and like turnips have been used since inaugural Halloween celebrations to make Jack-o-laneterns. The bitterness sometimes found in rutabagas is due to the presence of cyanoglucoside, which inhibits thyroid iodine transport, and may at high doses lead to hypothyroidism. The perceived bitterness is governed by a gene affecting one of our tastebud receptors, which also leads to perceived bitterness in turnip, broccoli, horseradish, and watercress. Luckily, I haven't yet found any of these vegetables bitter, so I believe I won't have to cross rutabagas off of my "edibles" list when I get a chance to eat them!