Horticultural Dictionary - Family

Genera are grouped into larger entities called families, some of which are easily recognised, others less so. Although families may appear at first to be of only academic interest, knowledge of the family to which an unknown plant belongs is the springboard to identifying it, and for the gardener, it can give an indication of the conditions required for successful cultivation.

The majority of families have always had names ending with the same group of letters, -aceae, and based on a genus within the family. This neatly distinguishes family names from genera and other plant groups. However, there are eight families with very well-known names which do not conform to this pattern. While it is perfectly acceptable to continue to use these names, the modern trend is to use alternative names with -aceae endings and this is what has been adopted in the RHS Plant Finder.

Family names contain plants with similar flowers but a wide variety of growth forms. Knowing the family helps with identification of unknown plants, e.g. Lamiaceae contains many plants with square stems.