Sea in culture of barbarian invaders and knowledge of geography took a backward step. In the seventh century, Isidore of Seville produced a "wheel map" in which Asia, Africa and Europe were arranged like segments in an orange, separated by the "Mare Mediterranean", "Nilus" and "Tanais" and surrounded by "Oceanus". It was not until the fifteenth century that Ptolemy's maps were used again and Henry the Navigator of Portugal initiated ocean exploration and maritime research. Encouraged by him, Portuguese navigators explored, mapped and charted the west coast of Africa and the Eastern Atlantic and this knowledge prepared the way for the great voyages
Sea beet Sea beet The sea beet, "Beta vulgaris" subsp. "maritima" ((L.) Arcangeli.), is a member of the family Amaranthaceae, previously of the Chenopodiaceae. Carl Linnaeus first described "Beta vulgaris" in 1753; in the second edition of "Species Plantarum" in 1762, he divided the species into wild and cultivated varieties, giving the name "Beta maritima" to the wild taxon. The sea beet is native to the coasts of Europe, northern Africa, and southern Asia. The sea beet is the wild ancestor of common vegetables such as beetroot, sugar beet, and Swiss chard. Its leaves have a pleasant texture and taste when served