Thesis (BS Biology) -- University of the Philippines Mindanao, 2011

The flowering habit of the nipa palm, Nypa fruticans, was studied through observation and experiments in its natural environment at different locations in Davao City and Carmen, Davao del Norte. A total of 58 inflorescences, 35 from different sites in Davao City and 23 from Carmen, were observed over a 10-month period. Nipa was found to be flowering throughout the year but only few palms were able to produce an inflorescence, most notably those with long access to sunlight. At full maturity, the inflorescence consisted of a long monopodial axis which ends with a pistillate (female) head. The pistillate head consisted of a cluster of closely packed female flowers arranged irregularly and spirally and exposed upon anthesis. Lateral branches were inserted spirally along the monopodial axis at irregular intervals terminated by staminate (male) rachillae. In Davao City, it took approximately 41.4 days for the inflorescence to reach male anthesis. Inflorescences in Carmen, Davao del Norte took 6.83 weeks to reach male anthesis from emergence, produces more male and female flowers with 33.22 and 61.3 flowers respectively. Also the staminate rachillae of inflorescences in Carmen were longer, averaging 7 cm. These inflorescence characteristics were all significantly different across locations when subjected to t-test indicateing an important role of environment in shaping their development. Additional 12 inflorescences from nipa stands in Talomo, Davao City were studied for stigma receptivity. Stigma receptivity was highest 12 hours after anthesis, gradually decreased with time that eventually dropped to 55% 48 hours after.