gynoecium [ ji-NEE-see-uhm, -shee-, gahy-, jahy- ] noun: the female reproductive organs of a flower consisting of the aggregation of carpels or pistils
carpel [ KAHR-puhl ] noun: a structure in a flower that contains an ovary (and one or more ovules), a stigma, and often a style; may occur singly or in a group
pistil [ PIS-tl ] noun: a carpel or group of fused carpels forming the female reproductive part of a flower and usually including the ovary, style, and stigma
pistillate [ PIS-tl-it, -eyt ] adjective: having a pistil or pistils but no stamens
ovary [ OH-vuh-ree ] noun: in a flower, the ovule-bearing, enlarged lower part of a pistil or gynoecium of an angiosperm plant that ripens into a fruit
stigma [ STIG-muh ] noun: in plants, the part of a flower’s carpel that receives the male pollen grains; generally located atop a style
style [ stahyl ] noun: in botany, the slender stalk that connects the stigma and the ovary
As we face the threat of impending loss of so many pollinators, gardeners benefit from understanding the terminology of the parts of a flower where pollination and fertilization take place. Many of us started our study of botany being taught that the male parts of the flower are the stamens, and the female parts are the pistils. Unisexual flowers that are female—they have pistils but no stamens—are referred to as pistillate. So how does the word gynoecium fit in? It is a collective word for the combined pistils or carpels of a flower and is its innermost whorl, where after fertilization, the seeds develop from the ovules within the ovary, which becomes the fruit. Successful fertilization (pollination) of flowers is critical to much of the world’s food production.
The word gynoecium originated from an alteration of the Greek word for women’s apartments or house. The word pistil comes from the Latin pistillum, meaning pestle (as in mortar and pestle) for its shape. The word carpel is derived from the Greek karpos that translates to fruit.
What is the difference between the carpel and the pistil?
The carpel is a unit of the gynoecium consisting of the ovary, style (when present), and stigma. The words carpel and pistil are often used interchangeably although they are not always synonymous. If a flower has a single carpel (monocarpellary), then it also has a single—simple—pistil. If a flower has two (bicarpellary) or more carpels (polycarpellary) that are distinct from each other, then it has an equal number of simple pistils. In these cases, when the carpels are freestanding, the gynoecium is apocarpous. However, if the multiple carpels in a flower are not distinct but rather fused together, then the flower has only one—compound—pistil and the gynoecium is considered syncarpous. In some cases, the number of styles, stigma lobes, or locules (chambers in the ovary) reveal the number of carpels in a syncarpous gynoecium.
Simple Pistil(s)
Left to right: The perigynous flower of native Prunus pensylvanica (pin cherry) has 10–30 stamens and one freestanding carpel. The close-up picture shows the superior ovary, style, and stigma of the simple pistil, which sits unattached in a hypanthium cup. The fruit is a drupe.
Left to right: The flower of Paeonia suffruticosa (tree peony) has up to 160 stamens and 5 distinct carpels. The close-up shows the superior ovary, style, and downward-facing stigma of a peony’s apocarpous gynoecium. The fruit is a follicle, which dehisces or splits along one suture..
Left to right: The flower of naive Aquilegia canadensis (wild columbine) has numerous exserted stamens and 5 free carpels. Each simple pistil has a superior ovary, exserted style, and stigma.. The aggregate fruit is an etaerio of follicles that contain shiny black seeds.
Left to right: The flower of native Magnolia virginiana (sweetbay magnolia) has 32–102 stamens (which have fallen) and 9–50 free carpels. Each simple pistil has a superior ovary, style, and stigma arranged on an elongated floral receptacle. The aggregate fruit is an etaerio of follicles.
Left to right: The flower of native Fragaria virginiana (wild strawberry) has 20–35 stamens in 3 whorls, and 30–150 free carpels. The close-up shows the superior ovary, style, and stigma of the simple pistils. The aggregate fruit—an etaerio of achenes—sits on an enlarged receptacle.
Compound Pistil
Left to right: The hypogynous flower of Cardamine hirsuta (hairy bittercress) has 4–5 stamens and 2 fused carpels. The close-up shows the compound pistil: a superior ovary, style, and stigma. The fruit is a silique that splits open into two valves.
Left to right: The epigynous flower of Hamamelis virginiana (witch hazel) has 4 stamens and 2 fused carpels. The compound pistil has a semi-inferior ovary and 2 persistent styles and stigmas. The fruit is a 2-seeded, loculicidal capsule..
Left to right: Tulipa gesneriana (Didier’s tulip) has 6 stamens and 3 carpels (tricarpellary) fused together. The close-up shows a superior ovary with a sessile stigma (style usually absent) whose 3 lobes indicate the number of carpels in the syncarpous gynoecium. The fruit is a loculicidal capsule.
Left to right: The flower of Passiflora caerulea (blue passionflower) has 5 stamens on a stalk (androgynophore) atop which sits a tricarpellary syncarpous gynoecium with 3 styles and stigmas. The fruit is a berry.
Left to right: The protandrous flower of native Geranium maculatum (wild geranium) has 10 stamens in 2 whorls and a compound pistil of 5 fused carpels. Each carpel base has a mericarp containing a seed and an elongate beak concealing the style column above which project 5 style branches. The fruit is a schizocarp.
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Related Words
- dichogamy: Learn how a flower might help to ensure successful fertilization by having its pistils and stamens mature at different times.
- hypogynous, perigynous, epigynous: Learn more about the position of the gynoecium in a flower to better understand the development of its fruit as well as to help identify a plant.
References
Aquilegia canadensis — red columbine. Cardamine hirsuta — hairy bitter-cress. Fragaria virginiana — common strawberry. Geranium maculatum — spotted crane’s-bill. Magnolia virginiana — sweet-bay. Narcissus pseudonarcissus — common daffodil. Prunus pensylvanica — pin cherry. Native Plant List. Go Botany. https://gobotany.nativeplanttrust.org/simple
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