University of Guelph, Guelph, Ontario N1G2W1, Canada.
Microsc Microanal. 2011 Feb;17(1):125-31. doi: 10.1017/S1431927610094043. Epub 2010 Nov 19.
Microscope and fiber-optic spectrophotometry of transmittance and backscattering both showed moss leaves to be capable of casting strong shadows, with a single leaf blocking approximately 90% of incident light from a point source. In leaves with only one layer of cells, the transmittance through the cytoplasm of single cells was similar to that for whole leaves. Analysis of cell wall birefringence by polarized-light interferometry indicated that cell walls might normally scatter rather than transmit light. Spectra transmitted through, or backscattered from, the upper green layers of moss were dominated by selective absorbance from chlorophyll, but there was also evidence of wavelength-dependent scattering, as detected in the lower layers of brown, dead moss. Specular reflectance from moss leaves was detected by polarimetry and may have contributed to the relatively high macroscopic transmittance of stationary moss in water. Shadowing by moss leaves was confirmed by dynamic measurements of mosses in turbulent water without bubbles. Flicker patterns from leaves were superimposed on the underwater flicker pattern created at the air-water interface, thus flecks of light were reduced in intensity, increased in frequency, and decreased in duration. This was detected with both point source and diffuse illumination of samples.
显微镜和光纤分光光度法的透射和背散射实验均表明，苔藓叶片能够产生强烈的阴影，单个叶片可阻挡约 90%的点光源入射光。在仅有一层细胞的叶片中，单个细胞细胞质的透光率与整片叶片的透光率相似。偏振光干涉测量法对细胞壁双折射的分析表明，细胞壁通常散射而不是透射光。通过苔藓上部绿色层透射或背散射的光谱主要由叶绿素的选择性吸收主导，但也有证据表明存在波长相关的散射，这在棕色、死亡苔藓的下部层中得到了检测。苔藓叶片的镜面反射通过偏振测量法检测到，这可能是静止在水中的苔藓具有相对较高的宏观透射率的原因之一。通过对无气泡的湍流水中苔藓的动态测量证实了苔藓叶片的阴影。叶片的闪烁模式叠加在气-水界面处产生的水下闪烁模式上，因此光斑的强度降低，频率增加，持续时间缩短。这在点光源和漫射照明样本时都被检测到。
