Krahm is the Thai name for a plant with the botanical name Indigofera tinctoria in the family Leguminosae. It flourishes especially during the rainy season and is utilized to extract a blue colour, used as a natural dye for dyeing seua mo hom (fig.).

The plant can grow to about well over a meter high and spread to a width of about 2 meter. Its has small light green leaves that have obtuse apices and that are arranged odd-pinnately on the branches.