MORPHOANATOMY, HISTOCHEMISTRY AND CRYSTALS OF THE UNDERGROUND SYSTEM OF BACCHARIS NOTOSERGILA (ASTERACEAE).

Background and aims: Baccharis notosergila is presented as a productivity-reducing weed in the fields of the Salado river basin, Buenos Aires, Argentina. The aims of this work were: to describe the structure of the underground system, the origin of sprouts, locate the secretory structures and storage substance to understand the adaptation strategies of this species as well as its ability to withstand chemical and mechanical control. M&M: The collected material was examined with conventional optical microscopy techniques. Histochemical tests to identify secondary metabolites were performed, and crystals were analyzed by a scanning electron microscope. Results: The subterranean system found was a xylopodium which has high shoot bud-forming potential. Storage substance was found to be inulin. Test for starch was negative. Resins and lipids (oil drops) were identified in ducts of roots; tannins and crystals of calcium oxalate were also found in the xylopodium and roots. Conclusions: The presence of these characteristics on the underground systems could explain the frequency of this species in the floristic from Salado river basin in which alternate periods of high humidity and drought. The belowground bud bank would be important to B. notosergila survival in this area with extreme climatic factors, and its resistance to mechanical and chemical control. Understanding the anatomical features of these plants is one of the steps to appropriate management of this species in the Salado river basin. [ABSTRACT FROM AUTHOR]