Origin and Composition of a Texture Layer on Seeds of Mungbean 1

The surface of mungbean seeds with a dull luster was observed to have a thick covering of cell‐like ridges and crosswalls which is designated the texture layer. Similar, but much less pronounced ridges were observed on seeds with a shiny luster. The thick texture layer of dull seeds could be removed by scraping and with a sodium hydroxide solution. In dull green seeds the texture layer was translucid, the green color originating from a shiny green seed testa underneath which was visible through the texture layer. In dull brown and brownish‐black seeds the texture layer contained a brown pigment which masked the green or green‐black mottled color of the shiny seed testa underneath. We suggest that the texture layer originates from the inner pod membrane Which contracts, becomes fractionated as it dries, and partly adheres to the seed surface. Therefore the texture layer is a reticulated deposit and not an outgrowth from the seed testa. Only thin remnants of the pod membrane maybe observed on shiny seeds, the amount depending on the depth at which the fracture of the membrane occurs. Chemical analyses support these observations. Tests of the texture layer for presence of waxes and pectins were negative. A test for carbohydrates was positive with quantity of carbohydrates in the texture layer from dull seeds three to four times that in the texture layer from shiny seeds. The component monosaccharides included glucose, xylose, arabinose, and galactose, supporting histological observations that the texture layer is made up of remnant cell walls.