Seasonal variation of leaf extracts of mistletoe (Phoradendron tomentosum)

Statistical analysis of gas chromatographic data using Microsoft Excel has been applied to the seasonal variation of leaf extracts of mistletoe (Phora dendron tomentosum) growing in Kerrville, Texas. Mistletoe samples were col lected from the same plant during the months of September 1995 through May 1996. Hexane extracts were analyzed by gas chromatography. When the normali zed chromatographic data were subjected to similarity index calculations, d efinite seasonal variation was observed with the most matches occurring in adjacent months and the most mismatches occurring in distant months. This m ethod appears to have value in determining the chromatographic peaks that m ight be avoided when seasonal variation is a concern. Compounds that are in dependent of parasitic host, season, gender and method of collection must b e carefully selected for use in biological analyses.