Micromorphology of the achene epidermis of Kobresia (Cyperaceae) revealed by SEM and its taxonomic significance

The taxonomy of the genus Kobresia is difficult and based on morphological characters. Achene micromorphology of the genus was studied with scanning electron microscopy (SEM), and its taxonomic significance evaluated. A total of 39 species and subspecies of Kobresia were included. The shape of epidermal cells of achenes is usually polygonal or rectangular. The anticlinal walls of the epidermal cells are mostly straight, rarely sinuous. Generally, a silica platform is formed on the inner periclinal wall of achene epidermal cell, and 1–3 silica bodies protrude from the middle of the platform. Sometimes, satellite silica bodies exist around the central bodies. The silica platform may be solid or perforated by pits. The micromorphological characters of the achene epidermis vary between different taxa. However, some closely related taxa show similarities. Therefore, the micromorphology of the achene epidermis of Kobresia is valuable in understanding the taxonomy at infraspecific, specific and supraspecific levels in the genus.