Botanically, flower parts are actually considered modified leaves. These highly specialized “leaves” are arranged in 4 whorls (rings of leaves that connect to the same point on a stem or stalk):

• Calyx – Sepals
• Corolla – Petals
• Androecium – Stamens
• Gynoecium – Pistils

Sepals

The sepals are the outermost ring usually seen below/outside the other flower parts. The sepals are the leaves that peel back from a flower bud. Sepals are usually green but they can be other colors as well. Calyx refers to the sepals as a whole.

Petals

Petals are the most recognizable parts of a flower. The petals are the second layer in the flower whorl and can be a wide variety of shapes, sizes, and colors, including green. Corolla refers to the petals of a flower as a whole. The calyx (sepals) combined with the corolla (petals) is called the perianth.

Stamens

The next layer, the stamens, are the male reproductive parts of the flower. Stamens are made up of anthers and filaments. The anther produces pollen and the filament holds the anther upright. Androecium refers to the stamens and their parts as a whole.

Pistils

The last and innermost whorl of a flower is the pistil – the female reproductive parts of the flower. A pistil is made up of the stigma, style, and ovary. The stigma is the outer part of the pistil where pollen is deposited. The style is the tube where pollen travels down and forms sperm cells. The ovary is where the egg is contained. In botany the egg is called an ovule. After being fertilized by sperm cells, the ovule grows into a seed. The other parts of the ovary then become the fruit. Gynoecium refers to the pistils and their parts as a whole.

Not All Flowers Are the Same

Not every flower has all 4 whorls. A “complete” flower means that it has all 4 whorls. A “perfect” flower means it has both pistils and stamens. Some flowers are imperfect and are missing either pistils or stamens. Some flowers are “incomplete” and may be missing sepals or petals. Some flowers have sepals and petals that are combined – these parts are then generally referred to as “tepals”.

Here are some additional terms used to describe flowers in relation to their whorls:

• Apetalous – no petals
• Apopetalous – petals are distinct
• Sympetalous – petals are fused
• Synsepalous – sepals are fused
• Adnate – Unlike parts are fused
• Free – Unlike parts are not fused
• Monodetheus stamens – filaments are fused, anthers are not
• Syngenesious stamens – anthers are fused, filaments are not
• Monoecius – The same plant has separate male and female flowers on it
• Dioecious – Separate male (only male flowers) and female (only female flowers) plants
• Synoecious – All flowers on the plant are perfect (both male and female)

Flowers can be standalone or arranged in a variety of ways. There is a lot of botanical terminology to describe the ways that flowers are arranged and the different parts of these various flowers. I am planning to go more in depth on these terms in a future blog. There are also so many ways that flower ovaries can develop into fruits. This will need its own designated blog to further explore as well!

If you are interested in learning how flowers transport their pollen to their stigma, check out my blog on the importance of pollination agents.