Lotus is a taxonomically difficult genus. No worldwide taxonomic studies for the whole genus have been produced since the monograph of Brand (1898). A comprehensive taxonomic revision of the genus is needed (Degtjareva et al., 2006). In Egypt, Lotus L. is represented by 18 taxa (Boulos, 2009). The species of Lotus constitute complexes of closely related groups with similar vegetative characters, including seasonal polymorphisms (Heyn, 1970), and it is difficult to distinguish among the species (Ojeda et al., 2009). Several studies have demonstrated the use of micromorphological characters to differentiate between some taxa