Early development and viability testing of embryos of Scirpus acutus Muhl

Scirpus acutus Muhl. is a hardstem bulrush found throughout North American wetlands. The seeds of most species of Scirpus have a relatively low germination potential. Seed viability and the developmental morphology of the embryo upon germination were studied using standard tetrazolium (TZ) testing, scanning electron microscopy (SEM), and standard light microscopy techniques. TZ indicates the majority of seeds are viable. Upon germination, a leaf is the first structure to elongate, emerge from the seed coat, and finally break through the pericarp. Following this stage, the radicle develops from an extension of the embryo axis located between the scutellum and the shoot tip of the embryo. The next leaf eventually arises at the junction of the sheath of the first leaf. The pericarp may act as a physical barrier and be a factor contributing to low germination in Scirpus acutus.