Sulcate pollen is shown statistically to be positively correlated with four primitive characters. There is some evidence that tricolpate pollen is more primitive than triporate. Polyporate pollen and polycolpate pollen are negatively correlated with two and six primitive characters, respectively, while multiaperturate pollen is negatively correlated with seven primitive characters. Evolution, therefore, has involved a progressive increase in the number of apertures. This conclusion is supported by the fossil record.