Micrographs of trichomes
Another feature of bean leaves is the presence of trichomes on both the top (adaxial) and the bottom (abaxial) leaflet surface.
It is said that historically bean leaves were used to remove bed bugs. Individuals would brush the bedding with the leaves and the bugs would become hooked on the trichomes. The leaves were then destroyed (Szyndler et al., 2013).
Below are pictures of those hooked trichomes.
These trichomes are not only found on a red kidney bean plant’s leaflet, but also on all the stems and other places. Take a closer look at Figs. 2, 5, 9 and so on.