Comparison of Phytolith Characteristics of Three Bamboo Species' Cotyledon Organs

Phytoliths are widely used in plant taxonomy, paleoecology, soil silicon cycling, and agricultural archaeology. Bamboo has a strong capacity for silicon absorption, and there are some phytoliths in various organs. In this paper, the leaf organs (leaf blade, leaf sheath, culm sheath, and culm blade) of three kinds of bamboos [B. vulgaris (Bambusa vulgaris), B. tulda (Bambusa tulda), and B. dolichoclada (Bambusa dolichoclada)] were studied; the content, concentration, particle size distribution, and morphological characteristics of phytoliths in leaf organs were analyzed to explore the differences of phytoliths in different functional leaf organs of bamboo. The results showed that the content and concentration of phytoliths were the highest in the leaf sheath and the lowest in the culm sheath, and the content and concentration of phytoliths in the leaf blade and culm blade were between them. For different bamboo species, the order of phytolith content was B. dolichoclada > B. tulda > B. vulgaris, while the phytolith concentration was the opposite. The highest values of phytolith particle size peak distribution in the leaf sheaths were the opposite to those in leaf blades, culm sheaths, and culm blades. The particle sizes of phytoliths of the three bamboo species showed a similar trend. Only a few larger phytolith particle sizes were distributed in leaf blades and culm blades when they were larger than 400 μm. A total of 25 types of phytoliths were identified, and the leaf sheaths were mainly elongate and rondel phytoliths. The leaf blades are mainly saddle and rondel phytoliths with a unique phytolith morphology. Culm sheaths are dominated by rondel, scrobiculate, and acute phytoliths. Culm blades are similar to leaf blades but have a characteristic phytolith morphology. In addition, saddle phytoliths were the most abundant in the leaf blade and the least in the culm sheath, while rondel phytoliths were the most abundant in the culm blade and the least in the leaf sheath. The parameters of long-saddle phytoliths are different in different bamboo species and leaf organs. According to the long saddle phytolith parameters of different bamboo species, different bamboo species can be quantitatively distinguished to a certain extent. Therefore, this study not only helps to understand the differences in phytoliths in different bamboo species and leaf organs, but also provides a theoretical basis for bamboo species classification.