Preliminary Report: Investigation of Castor Bean Investment in Extra-Floral Nectary Glands and Reproduction

Abstract

The castor bean plant, Ricinus communis has EFN (extrafloral nectary) glands that attract ants which provide defense for the plant. From this, we proposed the idea that the more EFN glands a plant has, the more ants will visit the plant, and therefore provide more defense to the plant. Using the principle of allocation, we deduced that a plant using this strategy would invest less energy in reproduction than in defense, given that growth is fixed. In this experiment we examined the number of reproductive flowers that a plant produces (male and female) in relation to the number of EFN glands on the petiole. We predicted that the more EFN glands present, the fewer flowers will be found on the plant. When comparing males and females, we found that there was instead a positive correlation between female flowers and EFN glands but no correlation between male flowers and EFN glands. From our results and analysis, we concluded that even though more energy was invested in defense (total number of EFN glands) the castor bean plant still produced more female reproductive flowers. These results contradict our assumptions based on the principle of allocation and reveals possibilities of control issues and biotic versus abiotic (chemical) discretion in defense investments.