14 - Spores and pollen in the marine realm

Abstract

Pollen and spores of plants are an allochthonous marine micropaleontologic group. They are the products of continental vegetation, and might best be considered as a biogenous component of fine-grained (5-150 μm) detrital or terrigenous marine sediment. Pollen grains are the male reproductive bodies (microgametophytes) in seed plants. They originate on the anthers of flowering plants, or angiosperms (like oaks, grass, and roses) and in the microsporangia of gymnosperms (pines, firs, and spruces). After pollination (transfer of the pollen grains to the female reproductive part) and fertilization (fusion of the sperm or male gamete with the egg or female gamete), the embryo develops within the ovule which becomes a seed. Coniferous pollen types were first described from the Pennsylvanian and angiosperm pollen from the early Cretaceous. Spores produced by “lower plants” such as algae, fungi, mosses, and ferns are some of the earliest preserved remains of plants. The Silurian marks the appearance of the first accepted spores with triradiate sutures. Spore production in primitive vascular plants, such as the club moss, may be homosporous, that is, a single type of spore is formed; or heterosporous. Heterosporous plants that produce male microspores and also the female megaspores are known since the late Devonian.