This article focuses on structural and morphological formations of lamellar single crystals in polymers. Even homopolymers that possess identical chemical repeat units never become fully crystalline (termed semi-crystalline, and a concept of crystallinity is introduced). In reality, these polymers have stopped short of a fully crystalline state. Although there is no single local barrier that is responsible for the stoppage, there is a range of essentially kinetic factors that hamper the macromolecules from becoming fully incorporated into the crystals. The basis of these factors arises from the long-chain nature of the molecules. Although polymer lallemar single crystals are true crystals based on any existing definition, they are always in a chain folded metastable state. The single crystals serve as the building blocks of aggregates growing on larger length scales such as dendrites, axilites, and spherulites. The significance of observing these single crystals and understanding their formation mechanism implies that both the growth rates and the shapes of the single crystals are important for understanding crystal growth mechanisms as well as the material properties of the polymer.