Germinability under natural temperatures of Lactuca serriola L. Achenes matured and collected on different dates from a natural population in the Negev desert highlands

Lactuca serriola L. achenes matured and were collected daily 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 daylengths, or in the dark. The importance of different germinability occurring under natural conditions in achenes matured on the same group of mother plants is discussed.