Learn to Identify Flower Parts

Ten Plant Parts that will Get You Started

Not to sound too cliché, but anything that seems difficult usually boils down to concentrating on the absolute first steps toward a goal. In the case of learning to identify plants, these first few steps involve simply learning the basic parts of a flower. You might be surprised to find that memorizing just ten parts will get you ready for using most any plant guide. The really good news is that all flowers—yes, all flowers—share most, if not all, of these ten parts.

Flowering plants (Angiosperms) are divided into two main groups: Composites (Asteraceae), and Everything else. The Aster group (some 25,000 species world-wide) is a group that usually gets set aside as a difficult group to identify, and while that may be somewhat true if you are working to species, the group is really quite easy to identify to family, and that is what we care about today. Bottom line: even the Aster family flowers are made up of the same ten parts with certain modifications.

Here are the Ten Parts You’ll Want to Know:

Pistil:

The pistil is the female reproductive part of a flower. It typically has a swollen base (ovary), the stalk (style), and a pollen-receptive tip, (stigma) which is often sticky. Some flowers have a single pistil, some have several to many. Each pistil is made up of one to many rolled leaflike structures called carpels. Noting the differences in the makeup of the pistil will help in classifying flowering plants.

Stigma:

The stigma is the top part of the pistil. It is usually sticky (sometimes hairy) because that's how it catches the pollen that will fertilize the ovules. The stigma can take on many shapes, depending on the flower species. In fact noting the shape is often part of keying a plant.

Style:

The style is the part of a pistil connecting the stigma and ovary.

Ovary

The ovary is the part where seeds (ovules) are located, waiting for pollinization. The pollen deposited by wind, insects, or other agent, will attach to the stigma and travel down the style to reach the ovary.
Ovules (the green circles in the drawing) are typically held in carpels, evolved from leaf structures that rolled to envelop and protect the ovules.

Stamens:

The stamens are the male reproductive parts of a flower; they produce pollen in terminal structures called anthers. The number of stamens is usually the same as the number of petals. They usually consist of a long slender stalk (the filament) with the anthers at the tip. Structures called nectaries are often found at the base of petals and provide food rewards to lure insect and bird pollinators.

Anthers:

Anthers are the pollen bearing structures atop the stamens, usually borne on a slender stalk called the filament. Each anther generally consists of two pollen sacs, which open when the pollen is mature. The method of opening, or dehiscence, is also a keying characteristic to note.

Filaments

The stalks that bear the anthers. A filament and an anther are collectively called a stamen. There isn't a whole heck of a lot more to say about filaments!

Petals:

The often colorful parts of a flower surrounding the reproductive parts (stamens and pistil(s). Petals use color and (usually) perfume to attract insects that pollinate the flower. The number of petals is consistant within a family: roses have five, buttercups have none, and lilies have three sepals, three petals, usually referred to as six tepals.

Sepals:

The sepals are modified leafs making up the first ring of flower parts. The sepals are collectively called the calyx and act as a protective covering of the inner flower parts in the bud. Sepals are usually green, but in some flowers (e.g., the lily and the orchid) they are the same color as the petals and may be confused with them.

Peduncle:

Peduncle is a rather fancy name for the stalk or stem of a solitary flower; the main stalk of a flower cluster. The word comes from the Latin "ped", foot.
Each of the flowers in a cluster may have its own individual stalk called a pedicel

Getting to know these parts will help you follow along any key in any guide. These parts are common to all flowers from the alpine reaches to Death Valley, and most every flower identification key is going to start by asking how many petals, how many sepals, stamens, and pistils, and then go into the arrangement of stamens. You must be clear on what parts are what parts! Buttercups have zero petals but their colorful sepals make them look like they do. A dogwood’s big white blooms are not petals either; those white parts are bracts (more modified leaves), and the flowers are in the center, almost like a sunflower.