Plants in the Araceae family are high in content of calcium oxalate (CaOx) hydrates. CaOx can be represented by three different mineral phases - whewellite (COM), weddellite (COD) and caoxite (COT).

Based on previous orientation research, 10 plant species were selected from the family Araceae. By purchasing from different commercial sources, 2 representatives of the same species were acquired in each case, so that they were not daughter plants or clones obtained by cutting.

Using polarizing microscope, crystals of CaOx were observed in 5 crosscuts per plant body of each species from the family Araceae. Three crosscuts were used from plant leaf and two from petiole parts.

In the transmitted light under the polarizing microscope, only idioblasts with raphides, druses and crystalline sand were identified – on the other hand, dipyramids, prisms and square-like aggregates were not observed. Therefore, the variability of morphological types is lower than in the data coming from the reflected-light microscope attached to the Raman spectrometer.

In plant leaves, calcium oxalate morphological types such as raphides and druses (composed of COM) were most prevalent. The most common morphological types in plants of the Araceae family were raphides and druses, which primarily consist of COM. Other, less common types such as dipyramids, prisms, and round or square aggregates, are typically composed of COD. The least frequently represent types were calcium oxalate trihydrate (COT) structures, including crystal sand and round or square aggregates.

This study showed that the CaOx hydration forms could be very effectively studied in vitro using Raman spectroscopy and confirmed their variations within different parts of the plant body. Therefore, it allowed further research of the CaOx cycle and the impact of the environment on the formation of CaOx; more studies would be, of course, essential for a more comprehensive understanding