Determining Evolutionary Relationships among Lycopsids Using Spore Wall Ultrastructure.

Abstract

Lycopsids are recognized as ancient seedless vascular plants that arose during the Early Devonian Period. Lycopsids demonstrate a variety of growth types, existing as both free-sporing herbs and 40 meter high trees that dominated many swamp forest landscapes. We aimed to determine evolutionary relationships among early lycopsids via a multilamellated area of spore walls that is present in the modern lycopsids Isoetesand Selaginella, as well as basal lycopsid fossils as old as 400,000,000 years.