vegetation, soil, and compost. At the end of the season, the soil and plants should be sorted to minimize the risk of accumulated disease. Genetic stock There is genetic diversity of this crop in the provinces of China; however further research is required. There is genetic similarity between Aralia cordata and Aralia hispida, as in prehistoric times there was a close connection between Eastern Asia and North America, facilitating the migration of plant species. The northern variation is less matured, with smaller stem hairs, fewer nodes, side shoots, and leaves than the southern variation, potentially caused by earlier flourishing. In domestic stocks there is not as much variation, although they are similar to the wild stocks of the south, which have shorter dormancy periods. Culinary use Japan The edible stem is sometimes boiled and served in miso soup. Despite its size, Aralia cordata is not a woody plant, as udo has a very soft stem, making it unsuitable for use as lumber. In addition, the stems become inedible if they grow too large. This fact is referenced in the popular saying udo no taiboku (), literally "great tree of udo", which is used metaphorically to refer to a person or object that is useless despite its large size. Young stems are consumed from the roots and added to soups and salads. It must be properly cooked, as the raw stems are coated in a resin tasting similar to pine. Prior to eating, they should be thinly sliced and boiled in water a few times or placed in chilled water for an hour to eliminate the resin. The stems may be cooked like asparagus. Korea The plant is called ttangdureup (, "land angelica") in Korean. Young shoots of spikenards are harvested during a month, from early April to early May, when they are soft and fragrant. In Korean cuisine, the shoots are commonly eaten blanched as namul, pickled as jangajji, pan-fried as jeon, or grilled as sanjeok. In Imsil County, they are also used for maeuntang (spicy fish stew). Dishes Ttangdureup-jangajji – a type of jangajji (pickle), made by blanching spikenards and pickling it. The pickling sauce is made by boiling the mixture of soy sauce, water, maesil-cheong (plum syrup), sugar, and vinegar with kelp, then cooling it. Ttangdureup-jeon – a type of jeon, made by blanching spikenards, coating them with starch and eggwashing them, then pan-frying them in oil Ttangdureup-maeun-tang