Elaiosomes in Urochloa paucispicata (Poaceae : Panicoideae : Paniceae): anatomy and chemical composition

The spikelet of Urochloa paucispicata has a typical Paniceae structure and it constitutes the unit of dispersal; the base of its lower glume is united to an elongated internode between the lower and the upper glumes, and at m aturity, it becomes soft and turgid, developing the elaiosome. Chemical identification of TLC fractions in the elaiosome of Urochloa pauci spicata showed that it contains triglycerides, free fatty acids and diglyce rides. Gas chromatography of the fatty acid methyl esters, of each fraction , showed the presence of palmitic, oleic, linoleic and stearic acids. Palmi tic, oleic and linoleic acids are significant components of the lipid fract ions. By field observations we identified three different species of ants (Hymeno ptera: Formicidae) which removed the spikelets of Urochloa paucispicata and carried them to their nests: Acromyrmex landolti fracticornis FOREL, Pheid ole spp. and Ectatomma spp.