Acrachne racemosa (B. Heyne. ex Roem. & Schult.) Ohwi of the subfamily Chloridoideae of the family Poaceae is an economically important grass species. Grasses are characterized by deposits of silica in the cells or tissues in the form of phytoliths which protect them from various types of biotic and abiotic stresses. Owing to variable shape and specificity of morphotypes, phytolith helps in taxonomical studies, reconstruction of paleoenvironments and prediction of climate changes. The present study focussed on developing a phytolith profile of the selected species. For isolation of phytolith, Dry Ashing Method was employed, and by epidermal peeling, in-situ location of phytoliths was deciphered. In the present study, silica percentage was studied from different parts of the plant and the maximum amount was found in the leaf. Frequency and morphometric data of phytolith morphotypes from different parts of the plants were also collected and analyzed. The strongest correlation was found between phytolith types of root and culm by Pearson’s correlation coefficient supported by cluster analysis. The saddle type of phytoliths had the highest frequency in the leaf; other types of phytoliths in different parts of the plant were bilobate, blocky types, elongate types, trapezoids, triangular, cross, sinuate elongate, tabular types, globular types. Functional groups and amorphous polymorphic phases of silica were also analyzed by FTIR and XRD. It was concluded that phytolith types are controlled by parts of plant body and by anatomical and environmental factors.

Plants grown close by roadside areas are exposed to variety of pollutants. Air pollution has an adverse effect on plants. Most air pollution comes from Automobiles. Automobiles have increased in number in tandem with population growth, as has pollution from automotive emissions. The first targets of these vehicular pollutants are roadside plants and roadway vegetation. Vehicle emissions contain a variety of contaminants that contribute to the worst types of pollution in the environment. Various contaminants from automobiles changed the properties of the vegetation that are exposed. One of the most obvious roadside plant is grass. This experiment shows how automobile emissions affect grasses anatomy and morphology. Experiments were conducted to investigate morphological as well as anatomical changes in leaves and culms of roadside grasses Triticum aestivum L. and Phalaris minor Retz. To carry out the experiment, samples (Fresh leaves and Culms) were collected from polluted sites and non-polluted site acting as a control. For anatomical study leaves and stems were cut into sections and epidermal peeling was performed in the laboratory and changes were identified under the light microscopy. SEM analysis was also done. Results revealed the major anatomical and morphometric variations observed in both Triticum aestivumL. andPhalaris minor Retz. growing in polluted and non-polluted study sites. Reduction in morphometric parameters for both the specimens growing in polluted study sites indicated a negative effect of pollutants on the growth of these pooideae members. Not only that changes in the anatomy of the polluted site specimens, both in the culm and leaf anatomy was found. SEM images of the abaxial and adaxial surface of the leaves showed micro-morphological changes, with stomatal size and number showing a reduction in case of Triticum aestivumL. for the polluted site specimens while the size of stomata showed an increase in the case of Phalaris minor Retz. growing in polluted study sites. These results highlighted the importance of anatomical and morphological data to determine the responsiveness of roadside grasses to various environmental pollutants.

Grasses (Poaceae) are the foremost silicon (Si) accumulators among terrestrial plants. Plants take up Si as monosilicic acid, Si(OH)₄, which polymerizes in cells and tissues such as the epidermis, xylem and phloem to form phytogenic (biogenic) silica, SiO₂ · nH₂O, deposited as phytoliths. This review, based on a documented literature search with explicit inclusion and exclusion criteria, evaluates evidence that phytoliths protect grasses against herbivores, fungal and bacterial pathogens and nematodes, and against drought, heat, salinity, metal toxicity, UV-B radiation and mechanical stress, and it examines combined stresses under climate change. We distinguish phytolith-specific evidence from studies that supplied soluble Si or Si nanoparticles, and we grade the evidence for each proposed mechanism. Physical mechanisms (abrasion, mechanical and apoplastic barriers, reduced non-stomatal water loss) are the best supported. Biochemical and hormonal mechanisms, including jasmonic acid, salicylic acid and ethylene signaling, remain hypotheses because Si(OH)₄ is chemically inert and much of the evidence is correlative. Elevated CO₂ can lower foliar Si concentration in some grasses, which may weaken protection, but effects on total Si accumulation and function are poorly known. Phytolith-occluded carbon is a potential but uncertain carbon sink. We identify research priorities and practical implications for crop, pasture and carbon management.