Genetic and nongenetic factors influencing deviations from five pappus parts in a hybrid between Microseris douglasii and M. bigelovii (Asteraceae, Lactuceae). - Vlot, ,E..C.,.; van Houten, ,W..H. J.,.; Mauthe, ,S.,.; and Bachmann, ,K.. (International Journal of Plant Sciences, 1992)