The notion of herbs as flavoring agents generally excludes those plants commonly known as vegetables, which are foods in and of themselves; that is, vegetables provide the substance, and herbs the seasoning. A related (and also imprecise) group of economic flora consists of the spice plants.
These are generally understood to be plants, usually native to the tropics, that bear aromatic fruits, seeds, or woody barks, and that are used, although not solely, to season foods. (Cooking spices may also have medicinal, aromatic, or pesticidal properties). Many of our favorite ornamental garden flowers such as the rose, foxglove, and garden heliotrope are old-time herbs. Whether incorporated into the flower border, or herb or kitchen garden, herbs are being grown for their pleasing scents, interesting colours and textures, and their pest-deterrent properties.