Spectral markers of terminal taxonomic nodes in Populus.

Table arranged by peak appearance in a given species group. The number of samples within a species group in which each peak appears is indicated in the last column. Retention time was rounded to the nearest 0.1 min. Pd = P. deltoides, Pf = P. fremontii, Pa = P. angustifolia, Pb = P. balsamifera, Pt = P. trichocarpa, dm = P. deltoides x maximowiczii. Mass accuracy was 2 ppm. Rt = retention time.