Size-Frequency Characteristics of Pinus echinata Pollen

Abstract

Size characteristics of P. echinata pollen were studied for 27 collections well representing the area of occurrence of the spp. For each sample the data include size-class frequencies and the mean, standard deviation, and standard error based on tube cell measurements of 150 grains of each collection. The size range of the means was from about 48 to 60 u, of individual grains from about 42 to 70u. Formed into an array, the data suggest the existence of a geographic cline of pollen-grain size in this sp. with the grains from the northeastern part of the area of the sp. having consistently larger mean values than those from the southern half of the area of the sp.