PLM:

These grains are extremely variable in size (12-29 µm x 13-30 µm); normally they are about 25 µm (12-50 µm) in diameter. About half of the grains are abnormal and deviate from the basic form, i.e., they are asymmetric and deformed. The granular surface of the irregular, tetraradiate grains is marked by crests and ridges. The ridges are 4-5 µm high. Spines 2.5 µm long and about 2.5 µm apart cover the surface. There are as many as 15 depressions (4-6 in abnormal), 3 containing about 8 µm diameter pores. The exine is on the thick side. The stain in Figure PA13-2 is fuchsin.

SEM:

These grains are extremely variable in size (12-29 x 13-30 µm); normally, they are about 25 µm. About half of the grains deviate from the basic form. The ridges shown at 1000X are 4-5 µm high. The surface spines (1000X and 10,000X) are 1-2.5 µm long and 2-4 µm apart. The surface is porous.