For centuries people have been attempting to make order out of the vast number of plants that exist in our world. In the most accepted organizational system, binomial nomenclature, there are many different levels.

For the home gardener, it is generally useful to know at least four of these levels. We start with the plant family which consists of a large group of plants that have a small number of characteristics in common. The genus (plural is genera) is a subdivision of the family and represents plants with several more common features. The species consists of plants that share several key characteristics and will freely interbreed with each other. The final level is the variety which is a naturally occurring variation of the species. When these are brought into cultivation, they are named and called cultivars. These plants are identical to each other.

Another naming system exists which consists of common names. The problem with them is that they can be different in different parts of the world. The botanical or scientific name of a plant in the binomial nomenclature system will be the same throughout the world. This helps avoid a lot of confusion.

Since this site is devoted to ornamental landscape plants we have generally only included plant generas which either survive or are used as annuals in the temperate regions of the world.

The buttons at the top of the page will take you to an index of all the families and genera featured by PlantsGalore.Com.