The Lesser Hemlock, also known as poison hemlock, is a toxic plant that can be dangerous to humans and animals alike. However, there are several other plant species that share some similarities with the Lesser Hemlock and can be used as its synonyms. Some of these plant species include the Water Hemlock, spotted cowbane, and death camas. While these plants may look similar to the Lesser Hemlock and also contain toxins, they differ in some aspects. For example, the Water Hemlock has a thicker stem and larger leaves than the Lesser Hemlock. It is essential to identify each plant accurately to avoid confusion and prevent unintentional poisoning.