1. Agwu COC, Osibe EE (1992) Airborne palynomorphs of Nsukka during the months of February–April 1990. Niger J Bot 5:177–185
2. Carlquist S (1976) Tribal interrelationships and phylogeny of the Asteraceae. Aliso 8:465–492
3. Cronquist A (1981) An integrated system of classification of flowering plants. Columbia University Press, New York
4. Dimon MT (1971) General problems raised by pollen of Mediterranean composites. Nat Monspel Ser Bot 22:129–144
5. Edeoga RO, Ogbebor NO, Amayo AO (1996) Pollen morphology of some Nigerian species of Aneilema R. Br. and Ludwigia L. New Bot 23:223–231