Underground system of Mandevilla atroviolacea (Stadelm.) Woodson (Apocynaceae, Apocynoideae) from the Brazilian high-altitude grassland

Abstract

The underground systems of plants show the most varied structures adapted to survival in unfavorable environ mental conditions. For instance, long-term droughts may induce the development of either water and reserve substances or vegetative propagation structures. Since Mandevilla atroviolacea is a species found at high altitudes on rocky outcrops, this study aimed to provide information on the morpho-anatomy of the underground system of this species that may assist in understanding the adaptive strategies at play. Samples from the underground system of three young and two mature plants collected in the field were sectioned and processed according to standard plant anatomical techniques. The upper area of the underground system corresponds to a xylopodium, while the lower is a tuberous stem organ. Tuberous roots account for the majority of the underground system. The increase in tuberous root diameter results from the action of a typical cambium. The high shoot-forming potential and storage of water and reserve substances observed in the underground system of this species are important strategies for it to survive in this habitat.