Geraniums and Pelargoniums belong to the family Geraniaceae, along with many other genera. All members of the Geraniaceae family have long pointed seed cases [fruit] that resemble the upright beaks or bills of the birds they are named for: Cranesbills – for true Geraniums, Storksbills – for Pelargoniums, or Heronsbills – for the lesser known Erodiums. The main botanical differences among these three can be found in their flowers. Geraniums have 5 regular petals while Pelargoniums, prior to hybridization, have two upper petals that differ from three lower petals. Erodiums have a different number of stamens.
Pelargoniums [Storksbills] are referred to and sold as annual Geraniums by nurseries and gardeners, while the true geraniums are referred to as perennial Geraniums. Pelargoniums are not hardy, having come mostly from South Africa and therefore adapted to Mediterranean and desert conditions. Some Pelargonium species come from Australia, others from East Africa and a few other places.
The Genus Pelargonium can be subdivided as follows:
A. Pelargonium hortorum (commonly called “zonals”)
1. Bedding geraniums with blooms that are single, semi-double, or double; solid or bi-colour
2. Novelty Blooms: Bird’s Egg; Cactus; Carnation; Painted Lady; Rosebud; Stellar; Tulip
3. Fancy or Ornamental Leaved: Gold, Silver, Bronze or Black leaved; mottled, bi-coloured or tri-coloured; butterfly leaved
4. Smaller forms of the above: Miniatures (3″-5″ tall), Dwarfs (6″-8″), and Semi-Dwarfs (9″ – 12″)
B. Pelargonium peltatum (commonly called “ivy geraniums”)
1. Blooms are single, semi-double, double or rossette, in solid or bi-colours
2. Fancy or ornamental ivy leaved
3. European type produce masses of single blooms, with narrower petals
4. Hybrids (sometimes called cascades) have zonal type leaves and blooms but a trailing habit
C. Pelargonium domesticum
1. Regal or Martha Washington Geraniums – huge azalea-like blooms
2. Miniature, Angels or Pansy-flowered – round flat blooms resembling pansies
D. Pelargonium species and primary hybrids
1. Originals do not resemble a “geranium” but rather look like succulents, e.g. P. echinatum – has thick grey stems with spines like a cactus and deeply cut grey-green leaves. The bloom is 5-petalled – 2 large uppers and 3 smaller lowers.
2. Scented Leaved, e.g. P. graveolens (rose scented) and P. tomentosum (peppermint scented)
True Geraniums [Cranesbills] grow in temperate climates on most continents. They tend to have a season in which they bloom, e.g. spring bloomers, summer bloomers and fall bloomers. With hybridization, some plants now have a longer flowering period or will re-bloom later in the season. Members of our society grow Geraniums in their gardens but generally do not present them at our annual shows, since they are usually not in bloom, and they would have to be dug out of the garden and potted – not very good for the plant.
If not dead-headed, these plants will set seeds which will sprout in the spring and the plants could take over your garden. Some also spread by underground roots, so it is important to keep control of the plants if you want to have other perennials in your garden. There are some sterile hybrids for sale, which are far less invasive.
Flowers may be white, pink, red, purple or blue. Some Erodiums also have blue flowers. Pelargoniums do not have blue flowers, having never had, or lost, the genes for this colour.
We refer to the Geraniums grown in Ontario as perennial. However, many true Geraniums will not survive Ontario’s winters. In England, many of these plants do survive the winter there. There are some lovely Japanese Geraniums, however again they will not survive Ontario’s winters. A shade loving Geranium from New Zealand would also be an annual in Ontario. There are collectors of true Geraniums that will over winter the tender Geraniums inside and take them back outside in the spring.
Seeds of the tender Geraniums are available from Plant World Seeds. It is interesting to take a tour of their Geranium seeds to see what a variety of plants are in this Genus.
Aside from Geraniums, other Geraniaceae include:
- Erodium [Heronsbill] – includes about 60 species, native to North Africa, the Middle East, Indomalaya and Australia; usually seen in rockeries and alpine gardens.
- Monsonia – includes about 40 species of herbs and undershrubs, some succulent-like, found in Africa, Western Asia and East India