Extrafloral nectaries of annatto ( Bixa orellana L.): anatomy, nectar composition and activity during organ development

ABSTRACT This study aimed to anatomically characterize the extrafloral nectaries (EFNs) of annatto (Bixa orellana) and determine the composition of its nectar in order to better understand their structure and function during organ development. Standard light and scanning electron microscopy techniques were used for anatomical analysis, and test-strips and a refractometer for determining nectar composition. Both receptacle and stem EFNs were found to possess similar anatomy and nectar composition, and to secrete from early to advanced developmental stages of the organs to which they are associa...