The column, or technically the gynostemium, is a reproductive structure that can be found in several plant families: Aristolochiaceae,

Orchidaceae Orchids are plants that belong to the family (biology), family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Orchids are cosmopolitan distribution, cosmopolitan plants that ...

, and Stylidiaceae. It is derived from the fusion of both male and female parts (

stamen The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

s and pistil) into a single organ. The top part of the column is formed by the anther, which is covered by an anther cap. This means that the ''style'' and ''stigma'' of the pistil, with the filaments and one or more anthers, are all united.

Orchidaceae

The stigma sits at the apex of the column in the front but is pointing downwards after resupination (the rotation by 180 degrees before unfolding of the flower). This stigma has the form of a small bowl, the clinandrium, a viscous surface embedding the (generally) single anther. On top of it all is the anther cap. Sometimes there is a small extension or little beak to the median stigma lobe, called rostellum. Column wings may project laterally from the stigma. The column foot is formed by the attachment of the lip to the basal protruding part of the column. One speaks of a mentum (chin) if the lateral

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 Etymology The term ''sepalum'' ...

s are also basally adnate (which are attached to the foot of the column). The column both releases

pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

and also receives it (from another individual) for fertilization. In the family Orchidaceae, unlike almost all other

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s, the single male anther at the tip of the ''column'' produces

that is not free and powdery but held in waxy masses of two, four or six pellets called '' pollinia''. The transfer of ''pollinia'' from one flower to another, though highly efficient, is often reliant upon one particular species of

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

s and it can be catastrophic for the population if its pollinator disappears from the community.

References

{{botany Plant morphology Pollination Orchid morphology