[Dormancy in Vicia loiseleurii seeds. Observations of the seminal tegument]

Seed coat structure has been examined in Vicia loiseleurii (M. Bieb.) Litw. on sections and phytoglyphs. The structure is the typical one of the Papilionaceae, with malpighian (= palisade) layer, hour-glass cell layer and hypodermis. An apparently non-cellular thick strip separates the seed coat from the cotyledons of the embryo. The malpighian cell of V. loiseleurii, with its cone-shaped cap or dome, is very similar to the well studied one of the Melilotus alba seed. Histochemical tests reveal the hydrophobic nature of the cap, which is stained by Sudan Blck B, Nile Blue and rendered highly fluorescent in its basal part by Auramine O. Aniline blue evidentiates callose in the wall below the cap. It is suggested that the impermeability of the coat, cause of the dormancy of the V. loiseleurii seed, is dependent on both the hydrophobic caps and the callose-containing radial walls of its malpighian cells.