There are several children's songs that herald the coming of spring by declaring that the nanohana has blossomed. Brilliant yellow fields of these first flowers of warm weather dot the countryside, and nanohana — young shoots of the aburana — are one of the first vegetables to appear on the vernal family table. Gastronomically, spring cannot begin without eating these sharp blossoms at least once.
Aburana (rape) belongs to the brassica family of mustards that includes plants grown for their leaves, such as Brussels sprouts, cabbage, collard, kale, kohlrabi and mustard; plants harvested for their roots, such as rutabaga and turnip; and plants grown for their edible stems and flowers, such as broccoli, cauliflower and nanohana. Rape, not generally eaten young and unpalatable when fully mature, rape is primarily grown in the West as a cover crop for foraging animals, especially sheep. Seeds of mature rape plants are also are turned into cooking oil or sold as birdseed.
In Japanese, "na" is the term for edible greens in general. Technically, young shoots or flowers of any of the brassica may be referred to as nanohana, but the name most commonly points to the young aburana (literally "oil greens"). Harvested in the early spring when yet immature and still tender, nanohana is enjoyed for just a few short weeks. Because of its strong association with early spring, nanohana is not hothoused and grown year-round like many other vegetables. Available therefore only once a year, the demand for the shoots during their short season is high and most restaurants feature nanohana in at least one dish.