The national flower of Scotland is the thistle, which has seven letters. The thistle is a prickly plant that has been associated with Scotland since the 15th century. It is believed to have been chosen as the national flower due to its ability to protect Scotland from invaders, as its prickly leaves would make it difficult for them to pass through. The thistle is also a symbol of strength and resilience, which is why it is still used today as a symbol of Scotland's national identity.