A study on functional and structural traits of the nocturnal flowers of Capparis spinosa L.

Functional and structural traits of the Capparis spinosa flower were studied in order to understand the mechanisms that allow this species to flower during the dry summer in the Mediterranean. Stomata were found on the abaxial surface of sepals, and on both the adaxial and abaxial surfaces of petals. Filaments and style were densely packed with small cells, exhibiting an increased density of cell wall material that provides strength. Petals possessed vacuolated parenchyma cells with large intercellular space. Turgor of petals was sustained mainly due to a decline in solute potential during the night and to a rise in water potential and solute potential at sunrise, concomitantly with a decrease in solute accumulation. Estimates of total sugars made in floral tissues of nine successive flowers along newborn stems were 100-fold higher than those of proline accumulation. Unsaturated fatty acids were identified as major components of lipids in petals, thereby influencing the fluidity of membranes.