Everything about Column Botany totally explained
The
column, or technically the
gynostemium, is a reproductive structure that can be found in several plant families:
Aristolochiaceae,
Orchidaceae, and
Stylidiaceae.
It is derived from the fusion of both male and female parts (
stamens and
pistil) into a single organ. 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 entire inflorescence).
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's 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
sepals are also basally adnate (= attached to the foot of the column).
The column both releases
pollen and also receives it (from another individual) for fertilization. In the Orchidaceae family, unlike almost all other
flowering plants, the single male anther at the tip of the
column produces
pollen that isn't 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
arthropods and it can be catastrophic for the population if its pollinator disappears from the community.
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