Gynoecium

Gynoecium (/ɡaɪˈniːsi.əm, dʒɪˈniːʃi.əm/; from Ancient Greek γυνή (gunḗ) 'woman, female' and οἶκος (oîkos) 'house'; pl.

: gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds.

The gynoecium is the innermost whorl of a flower; it consists of (one or more) pistils and is typically surrounded by the pollen-producing reproductive organs, the stamens, collectively called the androecium.

The term gynoecium is also used by botanists to refer to a cluster of archegonia and any associated modified leaves or stems present on a gametophyte shoot in mosses, liverworts, and hornworts.

[1] Gynoecium development and arrangement is important in systematic research and identification of angiosperms, but can be the most challenging of the floral parts to interpret.

[2] Unlike (most) animals, plants grow new organs after embryogenesis, including new roots, leaves, and flowers.

[note 1] A carpel is the female reproductive part of the flower—usually composed of the style, and stigma (sometimes having its individual ovary, and sometimes connecting to a shared basal ovary) —and usually interpreted as modified leaves that bear structures called ovules, inside which egg cells ultimately form.

Carpels are thought to be phylogenetically derived from ovule-bearing leaves or leaf homologues (megasporophylls), which evolved to form a closed structure containing the ovules.

Within the compound ovary, the carpels may have distinct locules divided by walls called septa.

Morphological and molecular studies of pistil ontogeny reveal that carpels are most likely homologous to leaves.

[citation needed] A carpel has a similar function to a megasporophyll, but typically includes a stigma, and is fused, with ovules enclosed in the enlarged lower portion, the ovary.

"[26] Basal angiosperm groups tend to have carpels arranged spirally around a conical or dome-shaped receptacle.

However, as Leins & Erbar (2010) pointed out, "the classical view that the wall of the inferior ovary results from the "congenital" fusion of dorsal carpel flanks and the floral axis does not correspond to the ontogenetic processes that can actually be observed.

All that can be seen is an intercalary growth in a broad circular zone that changes the shape of the floral axis (receptacle).

If the hypanthium is absent, the flower is hypogynous, and the stamens, petals, and sepals are all attached to the receptacle below the gynoecium.

Plant families with epigynous flowers include orchids, asters, and evening primroses.

In some cases a single ovule is attached to the bottom or top of the locule (basal or apical placentation, respectively).

In flowering plants, the ovule (from Latin ovulum meaning small egg) is a complex structure born inside ovaries.

The gap in the integuments through which the pollen tube enters to deliver sperm to the egg is called the micropyle.