This winter radish (
Raphanus sativus) belongs to the mustard family, (a.k.a. family Cruciferae or family Brassicaceae - plants with four-petaled flowers) which is a large group that includes
mustard,
wasabi,
cabbage,
radish,
broccoli, etc.
With the size and shape somewhat resembling a plastic 5-
liter coke bottle, it is called 大根("big root") in
Japanese.
Only the root is eaten most of the time, which is pure white except the top portion that has slightly green skin. It is served raw chopped, raw grated (daikon oroshi, which goes well with cooked fish), cooked, boiled, or pickled (see:
Tsukemono (Japanese Pickles)).
The earliest records of daikon date back to 2700 B.C. in
Egypt and 1100 B.C. in China, and even appears in
kojiki (the oldest Japanese literature ever found)
by its archaic name "oone", which is the
kun-yomi of the same
Kanji.
There were many varieties of daikon, until modernization in transportation and agriculture resulted in mass-marketing of only one type of daikon, the aokubi daikon (tr: "green-necked daikon").
Because of its coke bottle shape as mentioned above, it was best for efficient mass transportation. The plant suzushiro of
nanakusa fame is also now a rare type of daikon.
Here are pages with pics of it:
http://www.bsi.vt.edu/welbaum/hort4764/lessons/brassicaceae/slides/23-36.html
http://www.icon.pref.nagano.jp/usr/kohaku/daikonrui.jpg
http://www.icon.pref.nagano.jp/usr/kohaku/sandaikon.jpg
Sources:
http://www.icon.pref.nagano.jp/usr/kohaku/zatugaku.htm (in Japanese)
http://www.bsi.vt.edu/welbaum/hort4764/lessons/brassicaceae/lesson.html