Two species of Terfezia (T. arenaria, T. boudieri), two Tirmania speci
es (I: nivea, T. pinoyi) and Picoa lefebvrei were characterized by all
ozyme analysis. Only the Egyptian population of Tirmania, nivea appear
ed fixed like individuals in Tuber, while all the other species showed
heterozygosity suggesting reproduction via outbreeding. A clear diffe
rence arises between Terfezia, heterozygous for some enzymes, and Tube
r, always homozygous.