didynamous

Didynamous is a term used in botanical morphology to describe a flower whose androecium consists of four stamens of two distinct lengths: two longer stamens and two shorter ones. The name derives from Greek elements meaning “two” and “power,” reflecting the paired, unequal stamens.

In didynamous flowers, the long and short stamens are typically arranged alternately around the corolla. The long stamens often extend beyond the corolla (exserted), while the short pair may remain within the corolla tube or closer to it. The filaments and anthers can vary in length and exposure, but the characteristic two-long/two-short pattern is preserved.

This condition is relatively common across angiosperms, especially within the Lamiales, including many species in the mint family (Lamiaceae). It also occurs in other lineages such as Oleaceae and related groups. In floristic descriptions, didynamous stamens are a useful diagnostic character for identifying and distinguishing certain genera and species.

Functionally, the didynamous arrangement can influence pollination by positioning the pollen-bearing anthers to interact with visiting pollinators in specific ways, potentially affecting pollen transfer efficiency.

Related terms include tetradynamous, describing a higher-stamen pattern with eight stamens in two length classes, and other descriptive schemes that note variations in stamen number and length.