Plant Classification

Understanding plant classification, or taxonomy, is important for identifying plants. The scientific classification system with which I am most familiar has its roots in the work Systema Naturae by Carl Linnaeus (1700s), which categorizes plants based on physical characteristics. The classification system follows a set of rules to place plants into groups or categories in a hierarchical structure to show some relationship. Using a rose as an example, notice that the hierarchy moves from the top level (the plant family) through various categories to a specific rose, Rosa banksiae:

• Kingdom: Plantae (the plant family)
• Division: Magnoliophyta (or Angiosperms – a seed bearing plant, where the seed is not “naked,” but enclosed in ripened ovaries, or fruits)
• Class: Magnoliopsida (or Dicotyledonae – flowering plants that are not grassy or lily-like)
• Order: Rosales (one of the Dicots in the Magnoliopsida class)
• Family: Rosaceae (one of the families in the Rosales order)
• Genera: Rosa (one Genus in the Rosaceae family)
• Species: Rosa banksiae (a specific rose in the Rosa Genus; common name: Lady Bank's Rose)

Rosa banksiae (Lady Bank's Rose) photographed by J.A. Palmer.
New York Public Library, digital library (ID G92F023_026ZF).
This media file is in the public domain in the United States. This applies
to U.S. works where the copyright has expired, often because its
first publication occurred prior to January 1, 1923.

The scientific classification system has been modified many times over its two-hundred-plus year history, and is still undergoing change. Other systems have been proposed and tried. Many classification changes have been implemented as we learn more about genetics, and see relationships that were not as obvious when relying only on physical plant characteristics. While a new classification system evolves, the Family, Genera, and Species are the most useful categories for gardeners to understand and identify plants.