Foliar phytoliths as an aid to the identification of Paniceae (Panicoideae: Poaceae) grasses in South India

Abstract

Foliar phytolith studies were carried out in 13 genera including 29 commonly occurring species of the tribe Paniceae of the subfamily Panicoideae (Family: Poaceae) to determine the variations that exist in the phytolith characters, thereby assessing their value in identifying the species. Phytoliths were studied intact in epidermal peeling and also after isolation in acid medium. The members of the tribe were observed to produce a wide variety of lobate phytoliths including bilobate simple type, bilobate nodular, trilobate and polylobate. Ridged bilobate phytoliths produced by certain genera like Digitaria, Echinochloa and Sacciolepis are characteristic of the subfamily. Saddle shapes were not observed in any of the taxa under study. Shapes of phytoliths in the costal regions, their size, intercostal short cell silicification, nature of outer margins, presence of different appendages like papilla, microhairs, macrohairs and prickle hairs are important characters observed in epidermal peeling. Frequency percentages of different phytolith types occurring in isolated samples were also found to be reliable for taxonomic use. A key is prepared for the identification of all the 29 species studied. This could facilitate the identification of the taxa in the vegetative stage itself even when the spikelets are not available.