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Lactuca serriola L. achenes matured and were collected dairy when the pappi opened between July and October of 1989 and 1990, from a natural population of about 100 annual plants which germinated at the beginning of each winter in the Negev Desert highlands, Israel. Achenes collected every 2 weeks were mixed and stored together. Differences in achene germinability were observed when wetted during the next suitable season for germination and 1 year later, under natural temperatures and natural day lengths, or in the dark. The importance of different germinability occurring under natural conditions in achenes manned on the same group of mother plants is discussed.