Question: can all bay tree leaves be used in cooking

Answer: No, Some members of the laurel family, as well as the unrelated but visually similar mountain laurel and cherry laurel, have leaves that are poisonous to humans and livestock. While these plants are not sold anywhere for culinary use, their visual similarity to bay leaves has led to the oft-repeated belief that bay leaves should be removed from food after cooking because they are poisonous. This is not true; bay leaves may be eaten without toxic effect. However, they remain unpleasantly stiff even after thorough cooking, and if swallowed whole or in large pieces, they may pose a risk of harming the digestive tract or causing choking. There have been cases of intestinal perforations caused by swallowing bay leaves, so unless the leaves in the recipe have been ground they should be removed from the food before serving; otherwise, the risk of a surgical emergency remains. Thus, most recipes that use bay leaves will recommend their removal after the cooking process has finished.