( Erdtman, 1943) Describing the shape of a pollen grain or spore in which the polar axis is larger than the equatorial diameter. Comment: This term belongs to the system of shape classes suggested by Erdtman ( 1943, and extended in 1952), based on the measurements of the polar axis (P) and equatorial diameter (E). In this system prolate is defined as a ratio between the polar axis and the equatorial diameter of 1.33-2.00. See also: oblate, oblate spheroidal, P/E ratio, peroblate, perprolate, prolate spheroidal, shape classes, spheroidal, suboblate, subprolate, subspheroidal.