Perilla frutescens. This herb has been in use in Chinese medicine for thousands of years to treat morning sickness. It is a member of the mint family (Lamiaceae), and goes by a range of common names - Beefsteak Plant, Chinese Basil, Wild Sesame, Rattlesnake Weed, etc...
Shiso has a wide range of culinary uses, and shows up in Korean, Japanese, Thai, and Vietnamese cuisines. Its flavour is strong and distinctive, with notes of anise and cilantro. The leaves are often used raw, combined with other herbs such as mint and Thai basil, and fresh lettuce leaves.