Examples from the Web for tetradynamous
Tetradynamous, where a flower has six stamens, two shorter than the four, 101.The Elements of Botany|Asa Gray
The four inner stamens are longer than the two outer; and the stamens are hence collectively described as tetradynamous.
Thus in Cruciferous plants the staminal whorl consists of four long stamens and two short ones (tetradynamous).
Stamens mostly 6, tetradynamous (two inserted lower and shorter).