Bicellular trichomes called ‘microhairs’ are known as ‘salt glands’ in some Chloridoideae in the Poaceae. The adaxial leaf surface of a salt-tolerant grass, excretes salts, whereas the abaxial leaf surface does not. In this study, we investigated the morphology and excreting-function of the microhairs of , comparing the adaxial and abaxial leaf surfaces. Scanning electron microscopy of the leaf surfaces showed the distribution of microhairs on both sides and revealed significant excretion on the adaxial side but a small excretion on the abaxial side. Energy-dispersive X-ray spectrometry revealed that microhairs on the adaxial side excrete sodium, magnesium, and chlorine, whereas those on the abaxial side excrete or secrete insoluble substances, which sometimes contain silicon. Transmission electron microscopy was used to clarify the ultrastructure of microhairs, as in the first detailed report on spp.; however, the microhairs on both leaf sides showed typical structures of bicellular salt glands reported in Chloridoideae. The cap cells of the microhairs had smooth surfaces without epicuticular wax structures. These results indicate that the ultrastructural features of microhairs are important for understanding physiological mechanisms in common with salt-excretion and the excretion or secretion of other substances.

中文翻译：

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耐盐结缕草微毛的形态和排泄功能，比较正面和背面叶表面

被称为“微毛”的双细胞毛状体在禾本科植物中被称为“盐腺”。耐盐草的正面叶面会排泄盐，而背面叶面则不会。在这项研究中，我们研究了微毛的形态和排泄功能，比较了正面和背面的叶表面。叶面扫描电镜显示两侧有微毛分布，近轴侧有明显的排泄物，而远轴侧有少量的排泄物。能量色散X射线光谱分析显示，正面的微毛分泌钠、镁和氯，而背面的微毛则分泌或分泌不溶性物质，有时含有硅。透射电子显微镜用于阐明微毛的超微结构，如第一份有关物种的详细报告；然而，叶面两侧的微毛显示出虎杖亚科中报道的双细胞盐腺的典型结构。微毛的帽细胞具有光滑的表面，没有表皮蜡结构。这些结果表明，微毛的超微结构特征对于理解与盐排泄和其他物质的排泄或分泌相同的生理机制非常重要。