Common names are challenging for many reasons. Often the same common name is given to multiple unrelated species, even within one region, or one species has many different common names, or the local common name is different from a more widespread common name. Additionally, common names are often very botanically misleading, indicating plant families that are very distantly related, such as flowering plants given a “fern” name, many non-grass plants given a “grass” name, and many non-lily plants given a “lily” name, just to mention a few.
If you don’t know the scientific names for some of your species, there are databases that can be a good starting point to determine them. Some excellent global databases of plant names include Plants of the World Online, International Plant Names Index, and World Flora Online. Many regions and countries have also developed botanical descriptions of native plants, or other guides to local floras (online and/or as published books). The Biodiversity Heritage Library provides scanned copies of books for some regional floras. Other great resources might include any botanical gardens, herbaria, or universities in your region, which may have experts in plant systematics and taxonomy who can help you identify species with scientific names.