Morphological characteristics of phytoliths from representative conifers in China

Coniferous phytoliths in sediments are an effective tool for detecting the historical appearance of conifers. However, at the timberline in mountainous areas, such coniferous phytoliths are easily confused with grass phytoliths. This study analyses modern phytoliths from 17 conifer plants. Six common types and six rare types were identified. The conifers studied produce abundant blocky polyhedral and cubic (in the average 30–40 μm size range), blocky scrobiculate (average 30–40 μm), tabular elongate unsculpted (length 50–100 μm, width 10–20 μm), tabular elongate cavate (length 50–150 μm, width ∼10 μm), tabular elongate dendritic (50–100 μm × 10–20 μm), and irregular oblong (20–40 μm) phytoliths. This paper aims to show morphological characteristics of coniferous phytoliths in China, and to show how the common coniferous phytoliths differ from similar grass phytolith types, such as blocky polyhedral coniferous phytoliths from silicified parallelepipedal bulliform cells produced by grass. Blocky polyhedral and cubic phytoliths are the commonest coniferous phytoliths found in the sediments, but need to be carefully distinguished from grass parallelepipedal bulliform cells. This study indicates that clearly protruding ridges and irregular inward edges are essential features of cubic and polyhedral morphotypes produced by conifers. Results of this paper might provide important material for the study of paleovegetation and paleoecology of mountainous areas, especially at the timberline.