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Geranium (Pelargonium) Anatomy and Plant Parts

Janet has been passionately growing pelargoniums since a child. She's a member of the Geranium and Pelargonium Society.

Learn more about geranium (pelargonium) anatomy.

Learn more about geranium (pelargonium) anatomy.

Pelargonium Plant and Flower Parts: A Lesson in Botany

Getting accustomed to geranium (pelargonium) flower parts is important for the geranium lover but even more for the geranium hybridizer.

Just like us, geranium flowers are made of several “body” parts, and each of these parts has a name.

While all flowers are substantially made of the same parts, where these parts are exactly located and sometimes what shape they take can sometimes be a challenge to recognize.

Geranium flower parts are fortunately not very complicated to study as they are rather easy to identify and distinguish.

Pelargonium Flower Parts

Flowers, also referred to as blooms or blossoms, are simply the reproductive structure of plants. All plants known for producing flowers and seeds are referred to as “angiosperms.”

The term was coined in 1690 by German botanist Paul Hermann. It derives from the Greek word angeion, meaning “vessel” and spermos, meaning “seed.”

The anatomy of flowers can be divided into two distinct parts: the vegetative parts and the reproductive parts.

Below we will take a look at both categories of geranium flower parts, and we will also take a look at other parts of geranium plants.

Flower bud anatomy

Flower bud anatomy

The Vegetative Parts

The vegetative parts include the petals and other structures that include the corolla (which includes many petals often in attractive colors to attract bugs which aid in pollination) and the calyx (which includes several units known as sepals).

Sepals are green, leaf-like units that enclose the flower in the bud stage. Sepals provide protection to the flower when in the bud and support for the petals once opened. The term sepal was coined by Noël Martin Joseph de Necker in 1790.

The term sepal derives from the Greek word skepi, meaning covering. Collectively the sepals are referred to as the calyx, which derives from the Greek word kalyx, meaning a husk or wrapping.

Once the geranium flower is done blooming, the spent flower, along with its petals and sepals, wilts.

The calyx (the sepals) and the corolla (the petals) together form what is known as the perianth.

The perianth surrounds and protects the flower’s reproductive parts.

Not many people are aware that petals and sepals are simply modified leaves.

The pedicel instead is a stalk supporting a single flower.

The Reproductive Parts

As with several other flowers, geraniums are known for featuring flowers that are composed of "male" and "female" parts, which can be found on the same flowers. The scientific word for this peculiar characteristic is hermaphrodite.

The Male Parts

The male parts of geranium flowers encompass the stamens, brush-like structures formed by the "filament," which is comparable to a paint brush's handle, and the "anther," which is comparable to a pain brush's bristles covered with pollen.

When the pollen is ripe, it will typically appear fluffy and rich yellow or orange in color, and it will come off easily.

Generally, geraniums have seven stamens of unequal length, with five that are long and two that are short.

The Female Parts

The female parts consist of the pistil, which comprises the stigma, the style, and the ovary. The style, which is a tube-like structure, ends at the top with the stigma and at the bottom connects to the ovary.

The stigma is composed of several stigmatic papillae, which are cells receptive to pollen. At the most fertile time, the stigma will be covered with a sticky substance which will help the pollen adhere. This substance also works as an attractant for pollinating insects.

Once the pollen attaches to the stigma, as proven by Giovanni Battista Amici in 1830, a pollen tube grows, allowing two sperm nuclei to travel down, and one of them unites with the egg nucleus producing a zygote.

The other sperm nucleus instead unites with two polar nuclei producing an endosperm nucleus. What happens next is that the fertilized ovule matures into a seed.

The ovary, of course, is a very important part as it contains and protects the developing seeds.

Reproductive geranium flower parts—male and female parts showing on the same flower

Reproductive geranium flower parts—male and female parts showing on the same flower


More Geranium Pelargonium Anatomy

Geraniums, of course, aren’t solely made up of flowers. Just like other plants, geraniums are blessed with appealing leaves and other important parts.

Getting accustomed to these parts is advantageous, not only to satiate curiosity but also for the purpose of understanding exactly what parts of a plant are being described in articles and books.

Of course, we have the roots, which are anchored into dirt. The roots are meant to take in water and nutrients from the soil.

Then, above the dirt, there is the stem. The main function of the stem is to provide support to the geranium’s leaves, flowers, and seeds.

Leaves instead are there to photosynthesize (carbon dioxide is absorbed through the pores and oxygen is released), and such leaves, therefore, feed the plant with nutrients.

Leaves connect to the stem through a leaf stalk that attaches the leaf to the plant and is known as petiole.

A small appendage at the base of the petiole may be found, and this is called a stipule.

The angle formed between the upper side of the stem and a leaf is known as axil. Sometimes a bud may form here, and when it does, it is called an axillary bud.

The node is an area of branching of leaves, while the internode is the area between the branching.

At the opposite side of the roots, right atop the stem, is the terminal bud. Also known as the apical bud, this is the main area of growth in geranium plants.


Sources and Further Reading

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2022 Janet Rolla