Pelargonium tongaense          Geranium ‘New Hampshire Purple’


Shortly after getting interested in “geraniums” you run up against the issue of “which geranium?” you are talking about (or growing or

 looking for or researching or legislating about). On the simplest level - “Which geranium?” means what variety (or cultivar) are you talking

about? On a more complex level - “Which geranium?” means some greater degree of difference. The question becomes “Are you

 interested in ‘true geraniums’ or Pelargonium?” For the novice, this question may be truly perplexing.


To tackle this more complex question of Geranium or Pelargonium, you have to confront he use of common names and scientific names

(and in the long run, history). By common agreement amongst scientists, all living organisms are given a scientific name which consists

of two parts: the generic name and the species name (or specific epithet). The scientific name applies to one and only one “kind” of

species of organism be it plant, animal, bacterium or fungus. For humans our scientific name is Homo sapiens. Homo is our generic

name and sapiens is the name of our species. So your “geranium” will have some scientific name. (Also, by agreement and convention

 the scientific name is italicized in print or underlined when written.). In addition, the scientific name looks like some foreign language.

And, in fact, it is based on Latin – a “dead” language which is not now spoken by any ethnic group. Centuries ago in Europe, Latin was

the language of scholars. It was the language of educated individuals. It was a common language by which they could communicate with

any other educated person no matter what country they were from or what their first language or mother tongue might have been.


People interested in plants then began describing them in Latin phrases. As the world known to Europeans expanded and as explorers

ventured further and further afield, many new and different plants became known. The use of descriptive Latin phrases to distinguish

each of these new kinds of plants became very cumbersome. The use of a two-word Latin scientific name

evolved. Linnaeus (a very famous and influential Swedish botanist) in his two volume book called Species

Plantarum, published in 1753, attempted to pull together the names and descriptions of all known plants. He

used the “binomial (two name) system of nomenclature” in his works. Since then this system of two words for the

scientific names of organisms has been universally adopted by the scientific world. And 1753 is considered the

 starting date for the application of plant names.                                                       

                                                                                                                                          (Lower right image)   Top of page 676 of Linnaeus’  Species Plantarum showing the subgroup of Pelargoniums with 7 fertile stamens in the Class Monadelphia Decandria (translation: ten stamens united by their filaments into one group)


Linnaeus placed all the plant species in the geranium family in the genus Geranium. This included some 40 species. The common English

name for these plants was “Cranesbill” which referred to the distinctive structure and appearance of the ripening seed structures.

The names Doves foot, Pigeon foot, Storks bill, Herons bill and Crowfoot were also used for these plants. John

Gerard’s Herbal published in 1597 and expanded by Thomas Johnson in 1633 lists these common names for the

plants in the geranium family. While it was proposed as early as 1732 (by Dillenius) that some Geranium species were

so distinct that they should be in a different genus (namely Pelargonium), the formal transfer of these species from

Geranium to Pelargonium was made by L’Heritier in the late 1700s. However, this change in names was not accepted

by all botanists, writers and gardeners. H.G. Witham-Fogg (who wrote his own book titled                                                  (Above)  Illustration of Geranium

Geraniums and Pelargonium                                                                                                                                            from  Gerard’s Herbal (1633)


and published in 1975) believes that H.C. Andrews was important in the development of the name problem between Geranium and

Pelargonium. Andrews was a prolific and popular garden writer and illustrator, who produced his own two volume work on geraniums

in 1805/6, and he rejected the name Pelargonium. So the name geranium became firmly attached to all members of the family including

the most popular and widely grown garden plant namely the zonal, bedding or fish geranium. Today we would designate this

group of plants as Pelargonium x hortorum. (The ‘x’ indicates a species of hybrid origin.) So we are left today with some nomenclatural

confusion between the use of geranium as a common name applied to a number of related but distinctive plants in the geranium family

(Geraniaceae), Geranium – a scientific name applied to a group of closely related plants primarily found in temperate regions of the

Northern Hemisphere, and the genus Pelargonium, another group of closely related, frost-tender plants from the tropical and subtropical

areas of the Southern Hemisphere, especially southern Africa.




Pelargonium ‘Red Capri’    Geranium ‘Biokovo’                Erodium trifolium           Monsonia heliotropoides             Sarcocaulon  crassicaule


The difference between the four or five genera commonly recognized in the geranium family (Geraniaceae) are fairly distinct. With a

minimum amount of botanical knowledge, you can easily determine which plants are growing in your garden or in a nursery.

1. Pelargonium. If the flowers on your plant are irregular (zygomorphic or bilaterally symmetrical), that is, if they have two petals different

in size and shape from the three other petals, your plants are in the genus Pelargonium. (In addition, these flowers have a

floral tube at the base of the flower and there are fewer than 10 stamens.) 2. Geranium. If the flowers are regular (all five petals are the

same color, size and shape) and have 10 stamens, then your plant is in the genus Geranium. 3. Erodium. If the flowers are regular

and the number of fertile stamens is five, then you have the genus Erodium. 4. Monsonia. If your plant has regular flowers, 15 stamens

and is herbaceous, then you have got Monsonia. 5. Sarcocaulon. If your plant has regular flowers, 15 stamens and the stem is succulent

and spiny, then it is Sarcocaulon. (Some botanists do not recognize this difference between Monsonia and Sarcocaulon, and all the

 species of Sarcocaulon are included in the genus Monsonia.)


Gerard’s Herbal (1633 edition) illustrates 17 different cranesbills all in the genus Geranium. Also included is Geranium Indicum

noctu odoratum (the night scented geranium from India) which he named the “sweet Indian Storks bill or painted Storks bill” and

which we now know as Pelargonium triste! All the other plants are European natives and remain in the genus Geranium.

Although Linnaeus, in his Species Plantarum (1753), included all members of the geranium family in the genus Geranium, he did

separate all the species of Pelargonium in a subgroup of plants with seven fertile stamens; Erodium was another subgroup recognized

by five fertile stamens; and the remaining “true” geraniums were in the last subgroup with 10 fertile stamens.



Recommendations have been made to regularize and make consistent, the use of the names Geranium and Pelargonium. At the

scientific level, there is no problem. The differences between the two genera are several and distinct. Modern studies further confirm

the distinctness of the two groups. There is no confusion between species of Geraniumand Pelargonium. The confusion arises with the

use of the word “geranium” as a common name. The use of geranium as a common name has the problems associated with all

other common names – that is, the name refers to several (or in this case, many) different plants and species. This pitfall is probably most

serious for the novice gardener; and it clearly will be a problem in communication for nursery workers, magazines, newspapers

and master gardeners staffing question and answer services. With the use of some descriptive prefixes communication using common

names can be facilitated and made more precise. Hardy geraniums, zonal geraniums, regal geraniums, scented geraniums get us on

the same page. To change the common usage of a long standing name like geranium is truly an optimistic but probably unrealistic goal.

Although it can happen. At least in the U.S we have seen the virtual disappearance of the word “poinsetta” and its replacement

with the more correct “poinsettia.” So we writers should keep trying and promoting the most correct use of words and terminology.

© 2010, Central Coast Geranium Society (CCGS )