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A hypothesis to obtain a mathematical expression to define the water flow through conductor tissues, regarding the water potential difference between top and bottom sites of the plant, was proposed from physic characteristics of xylem elements. The xylematic embolism incidence on the hydraulic conductance was kept in mind in the theoretical development. A simulation of water current by xylem way and the Percent Loss Conductivity (PLC) was made with values from bibliography. The results of the model were analyzed from biophysical and physiological point of view as well as the incidence of this phenomenon at water stress situations. [ABSTRACT FROM AUTHOR]

This letter addresses the indigenous discourse on a set of plant species used by the Witoto Indians of Northwest Amazonia to extract ash or vegetable salt, obtained from the combustion of the tissues of vegetable species, filtering of the ashes, and desiccation of the resulting brine. It aims to demonstrate how the study of the human condition is carried out through a reading of natural entities. The method employed is the indexical analysis of a discourse uttered by the elder Enokakuiodo in the Witoto language from 1995 to 1998, in a verbal genre called rafue , one of several genres of the ‘language of the yard of coca’. The species used to extract ash salt are conceived of as coming from the body of the Creator and as an image of the human body. The rafue of salt performs, in words and gestures, a narrative of human affects and capacities by reading ecological, biological, cultural and linguistic indices from a set of plant species. This discourse on plant species is a discourse on the control and management of bodily affects and capacities, represented as ash salts, that are lessons about sexual development which the Creator left for humanity as a guide—a ‘sexual education’.