METHOD: Glycoalkaloid Assay METHOD NARR: Individual glycoalkaloids were characterized by TLC and comparisons made with standards. Aglycones were characterized by TLC and GLC as described in Sinden et al 1980. Total glycoalkaloids a titration method, see Fitzpatrick & Osman 1974. RESULTS NARR: Authors discuss taxonomy and geographical considerations. Wild species have higher levels of TGA than cultigens and conspecific weeds. Glycoalkaloid patterre closer across species lines than within mga alone and show distinct geographical patterns. Peruvian species assigned to this series stand out chemotaxonomically. Sgr has a unique glycoalkaloid pattern. AUTHOR EXPLANATION: collected and GH-grown material and between large and small tubers make comparisons using TGA content difficult.