A Comparison of the Chemical Composition of Injured Leaves in Contrast to Uninjured Leaves of Victoria amazonica (Nymphaeaceae)

The object of this paper is to describe chemical and mineralogicalchanges in Victoria leaves that have sustained insect damage. Of 44 elements detected in various plant parts of Victoria amazonica(Poeppig) J. de C. Sowerby (V. regia auctt) Nymphaeaceae, only15 elements showed statistically significant differences inconcentration between insect-damaged leaves and whole (undamaged)leaves of the same plants. Two different types of insect damagewere noted: one was clearly recent, while the other was clearlyolder, probably not differing in time more than three weeks.Mg, Ca, Al, Si, S, Fe, Mn, Li and Ce were significantly moreconcentrated in the damaged leaf sections than in undamagedleaves of the mature plants with unopened buds. In the caseof preflowering plants, Na, Mg, Ca, Al, Si, S, Cl, Fe and Mnwere more prevalent in the damaged tissue than in the unattackedleaves of the same plants. In the former case, Na, K, Cl andP are rapidly lost when damage occurs, while plants that havehad a chance to recover from the damage, as in the case of thepreflowering plant leaves, begin to make up the difference inelemental concentration between the damaged and undamaged leaves. Mineralogical investigation showed that the amount of calcite(CaCO₃), the calcium oxalates weddellite and whewellite, andthe siliceous minerals - low-form cristobalite opal, low-formtridymite opal and quartz-was higher in the recently injuredleaves than in those that had been injured some time previouslyor than in the uninjured leaves. It is hypothesized that theincreased precipitation of minerals resulting from injury ispart of the plants' defence mechanism against further attackby insects or animals. Insect injury, Victoria, leaves, inorganic composition, mineralogy