Characterization and macropattern of calcium oxalate phytoliths in Argentinean endemic species of Chenopodioideae (Amaranthaceae)

Abstract

The Chenopodioideae comprises species with a worldwide distribution, mainly confined to xeric or saline areas. Calcium oxalate crystals (calciphytoliths) are abundant in these species and relatively poorly studied. The aim of this work is to characterize the different types of calciphytoliths and describe their macropattern in Atriplex undulata, Nitrophila australis var. australis and Suaeda divaricata (Chenopodioideae). Mature leaves of the three species were collected in Salitral de la Vidriera (Argentina), killed and fixed in formalin-acetic acid-alcohol and processed using common techniques for anatomical studies and crystal macropattern identification. Cross sections of A. undulata show that crystals occur subepidermically in the chlorenchymatic tissue while in N. australis var. australis and S. divaricata they occur deeper in the aquaeous tissue. Only A. undulata has two types of crystals: prisms and druses. The latter may be of two kinds: druses type A1 and B according to the shape of the individual crystals involved. N. australis var. australis presents type A1 druses while S. divaricata has a third type, A2. In cleared leaves of A. undulata and N. australis var. australis crystals can be observed in intercostal areas; in S. divaricata they are associated with the vascular bundles. The characterization of crystals and their macropatterns are useful for the identification of these species, which indicates their taxonomic value.