I think this what the women's soccer team is called, but I'm not clear on it.
It is short for
大和撫子 (yamatonadeshiko), which refers to the stereotypical attributes (particular kind of beauty and purity, etc.) that are traditionally considered to be observed among ideal Japanese women. It also refers to Japanese women with such attributes. The male counterpart is
日本男児 (nippondanji). This meaning was derived from the plant name ナデシコ as Dave points out. The
ヤマト (yamato) [old name of Japan] part was added in order to distinguish it from
It's a nickname for the Japan women's World Cup team: http://ja.wikipedia.org/wiki/%E3%82%B5%E3%83%83%E3%82%AB%E3%83%BC%E6%97%A5%E6%9C%AC%E5%A5%B3%E5%AD%90%E4%BB%A3%E8%A1%A8