If you are checking for the correct full botanical name of a plant or need the correct spelling of it, or wonder if your plant might have more than one name, or want to know just how the plant naming system is organized, then the RHS Planfinder is a great place to look it up. The Royal Horticulture Society offers a search function that provides thorough results. Also included are such arcane references as reverse synonyms for instances where, for example, a plant has been moved from one genus to another. Wonderful grist for those addicted to plant nomenclature and taxonomy, highly useful for the rest of us.
Hydrangeas are in their full glory right now -- I recently saw many breathtaking specimens during a drive along the Delmarva Peninsula, and they are numerous throughout the Washington, DC area, too. But I have had so many questions about how to care for them, how to change their color, how to make them bloom, it's almost amazing to me at this point that any of the hydrangeas out there are blooming at all. So, if you are among the many who are wondering about the proper care and feeding and pruning of your hydrangea, or want to know which kind might be a good choice for your yard, there is a good place to begin your research: the Ohio State University Extension online publication called "Hydrangeas in the Landscape." It discusses selection and care of numerous different hydrangea species and cultivars, including several of the hardier ones that grow successfully in more northern, colder areas of the country. Here's the address: