Foliar morpho-anatomy of Araujia odorata (Apocynaceae - Asclepiadoideae) in an altitudinal gradient. Histochemistry of laticifers

Araujia odorata is a sub-shrub native from Argentina, Brazil, Paraguay and Uruguay, whose latex, roots and leaves are used in traditional medicine. The objective of this work is to study the foliar morpho-anatomy of six populations in an altitudinal gradient (359-2155 m.a.s.l.) of Northwestern Argentine and to determine the nature of the compounds present in the laticiferous of the stems and fruits using conventional techniques for plant anatomy. The populations under study did not show significant morpho-anatomical differences. They presented simple leaves, pinnated brochydodromous venation, amphiestomatic isolateral lamina, brachy, anomo and amphicyclocytic stomata, eglandular trichomes, midvein with bicolateral vascular bundle and non-articulated laticifers continuous in the petiole, stem and fruits. Differences in the quantified foliar parameters are observed, however, only the density of trichomes, stomata and the thickness of the cuticle are positively correlated with the altitudinal gradient, indicating phenotypic plasticity. Histochemical analysis of laticifers and other stem idioblasts of A. odorata was performed for the first time.