As part of our special REI environmental series, “RadioNature,” we take you to the Bronx, an urban borough bordered by the Bronx River. It’s the only freshwater river that runs through New York City. And for the majority of low-income Bronx residents, it’s one of their only connections to nature and a break from urban life. And we go to San Francisco to visit Charles Garcia, a third generation “curandero,” a traditional healer in the Latino community who founded the California School of Traditional Hispanic Herbalism.