Several species of flora and fauna are considered national symbols. Oak (''Quercus robur'', ), and linden (''Tilia cordata'', ) are Latvia's national trees and the daisy (''Leucanthemum vulgare'', ) its national flower. The white wagtail (''Motacilla alba'', ) is Latvia's national bird. Its national insect is the two-spot ladybird (''Adalia bipunctata'', ). Amber, fossilized tree resin, is one of Latvia's most important cultural symbols. In ancient times, amber found along the Baltic Sea coast was sought by Vikings as well as traders from Egypt, Greece and the Roman Empire. This led to the development of the Amber Road.