Silicified bulliform cells of Poaceae: morphological characteristics that distinguish subfamilies

Abstract

Background: Grass phytoliths are the most common phytoliths in sediments; recognizing grass phytolith types is important when using phytoliths as a tool to reconstruct paleoenvironments. Grass bulliform cells may be silicified to large size parallelepipedal or cuneiform shaped phytoliths, which were often regarded as of no taxonomic value. However, studies in eastern Asia had identified several forms of grass bulliform phytoliths, including rice bulliform phytolith, a phytolith type frequently used to track the history of rice domestication. Identification with a higher level of taxonomic resolution is possible, yet a systematic investigation on morphology of Poaceae bulliform phytoliths is lacking. We aimed at providing a morphological description of bulliform phytoliths of Poaceae from Taiwan based on morphometric measurements in anatomical aspect. The results are important references for paleo-ecological studies. Result: The morphology of grass bulliform phytoliths is usually consistent within a subfamily; the end profile is relatively rectangular in Panicoideae and Micrairoideae, whereas cuneiform to nearly circular in Oryzoideae, Bambusoideae, Arundinoideae, and Chloridoideae. Bulliform phytoliths were seldom observed in Pooideae. Certain morphotypes are limited to plants growing in specific environments. For example, large, thin, and pointed bulliform phytoliths are associated with wet habitat; Chloridoideae types are mostly from C4 plants occupying open arid places. Conclusion: Grass bulliform phytoliths can be identified at least to the subfamily level, and several forms were distinguished within large subfamilies. Previously un-reported silicified cell types, i.e., arm cells and fusoids, and two special trichome phytolith types associated with bulliform phytoliths, were described. Morphometric methods were great tools for delimiting morphotypes; with refined morphological classification the association between forms and habit/ habitats was revealed. The knowledge provides new ways to interpret phytolith assemblage data, and it is especially useful when the sediments are enriched in large blocky phytoliths.

Foliar element distributions in Guadua bamboo, a major forest dominant in southwestern Amazonia

“…We found high silica contents in bulliform cells, bilobate and saddle-shaped short cells, and stomata (Figs. 1,2,3,4,5,6), thereby agreeing with earlier studies [25,27,28]. Silica is moderately high in the bundle sheet (Fig.…”

“…Bamboos together with other members of the Poaceae family are intriguing for detailed element mapping because they commonly form silicophytoliths in bulliform cells, long and short cells and hair cells [27,28]. The other anatomical positions of bamboo foliar phytoliths, though fewer, include the mesophyll, tracheid and vascular tissues [27].…”

Phytoliths as an indicator of change in vegetation related to the huge volcanic eruption at 7.3 ka in the southernmost part of Kyushu, southern Japan

“…The B ulliform F labellate phytoliths (ICPN 2.0) were further divided into five sub-types; Sasa -types, Pleioblastus -types, Bumbusoideae-types, Andropogoneae-types, and others, following Sugiyama and Fujiwara (1986) and Kondo (2010). We used the term indicating each part of these phytoliths defined by Fujiwara (1993) and Chen et al (2020). Identification criteria of these sub-types are as follows.…”

“…The eruption at 7.3 ka (KCE) definitely influenced the vegetation in the study region, as explained in the previous section. Modern observations show that pyroclastic flows usually damage vegetation more severely than other types of tephra (Dale et al, 2005). The distribution of pyroclastic flow (K-Ky) and the reconstructed vegetation type at each site before and after the eruption are shown in Figure 7a-c, to assess the influence of pyroclastic flow on the vegetation in each area.…”

“…Sasa grasslands were replaced by Andropogonea grasslands (probably of the genus Miscanthus). This is probably because herbaceous species are more vulnerable than arboreal species and thus were more severely affected by the volcanic eruption (Dale et al, 2005). Even weaker pyroclastic flows would have devastated the Sasa grasslands, allowing Miscanthus grasslands to flourish as the vegetation in the primary stage in vegetation transition after an eruption.…”