The key to trees, shrubs and lianas in the Belgian Flora: history, structure and changes in the new 2023 edition. This contribution documents the history and design of the determination key for trees, shrubs and lianas in the Nouvelle Flore de la Belgique / Flora van België . Ever since the first edition of the Flora, this key has been separate from the keys for families, genera and species. Its use of predominantly vegetative traits makes it complementary to the other keys. All woody species and climbers keyed out in previous editions of the Belgian Flora were always in the key to trees, while only part of them are included in the keys to families, genera and species. About half of the taxa in this key occur only cultivated, a smaller proportion are naturalised taxa or escapes from cultivation, and in last place are the native taxa. In this version, native and feral taxa were added consistently for the first time. The main change is the addition of 32 new taxa. ...