Rape shoots are the immature stems and buds of the rape plant. It is a vegetable representative of early spring, when you can see whole fields of the typical yellow nanohana flowers swaying in the breeze. This is a sight that has often been celebrated in haiku, for example this one by Buson:
rape flowers -
the moon in the east
the sun in the west
Nanohana ya | tsuki wa higashi ni | hi wa nishi
Buson here describes a vast expanse of rape flowers: between the moon rising in the darkening sky in the east and the sun sinking in the still bright west, there is nothing but a great field of yellow flowers (for this and other nanohana haiku, see R.H. Blyth, Haiku: Spring, p. 592-6). Nanohana is a kigo (season word) indicating "early spring."
Nanohana is one of the oldest vegetables cultivated in Japan. It is closely related (but not identical) to the rapeseed in Europe and America, but as a member of the Brassica family, it has also links to broccoli - in fact, the florets of nanohana resemble tiny broccoli. In contrast to the West, where rapeseed is only grown for its seeds from which oil is extracted, in Japan the spring shoots of the plant are used on the table. This is our nanohana, which literately means "flower of vegetable." The mature plant is called aburana, and this is used for oil as in the West (natane abura - see my post on cooking oils).
The entire vegetable of nanohana is consumable, not only the young buds which are just about to blossom, but also the stem and leaves and even the yellow flowers. Nanohana has a slightly bitter taste.
Nanohana is sold in Japan in February and March.
Nutritionally, it is high in vitamin C and also contains various minerals.
When keeping nanohana, it should be boiled and then put in the refrigerator. It cooks rather quickly, so be careful not to overcook.
A typical side dish is nanahana no karashi-ae (cooked salad dressed with mustard), as on the picture below. Nanohana is also used in tsukemono (pickles).
[Nanohana no karashi-ae]