COMMENTS ON GERANIUMS AND PELARGONIUMS
BY WAYNE L. HANDLOS, PH.D.
Pelargonium tongaense Geranium ‘New Hampshire Purple’
IN THE BEGINNING …
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.
GERANIUM OR PELARGONIUM
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
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
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
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.
WHAT HAVE I GOT?
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.)
WHAT DID HE KNOW AND WHEN DID HE KNOW IT?
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.
YOU SAY GERANIUM, I SAY PELARGONIUM
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.