Grass vegetative parts

Kestose and its isomer isokestose occur in the vegetative parts and seeds of grasses. These two trisaccharides consist of a fructose residue attached to a sucrose molecule. 

Polysaccharides are macromolecules which make up a large part of the bulk of the vegetable kingdom. Cellulose and starch are, respectively, the first and second most abundant organic compounds in plants. The former is present in leaves and grasses the latter in fruits, stems, and roots. Because of their abundance in nature and because of contemporary interest in renewable resources, there is a great deal of interest in these compounds. Both cellulose and starch are hydrolyzed by acids to D-glucose, the repeat unit in both polymer chains. 

What was good about the NVESD tests in Croatia was that vegetation was part of the test. When a local farmer accidentally cut a part of the test site s long grass, we suddenly found no explosive near the mines but when Mark Fisher, of Nomadics, took the Fido to the heap of cut grass, he had immediate positive tests in the cut grass. 

This laboratory experiment describes the preparation of a vegetation sample (e.g., grass) for radiochemical analysis. The sample is dried and ashed. In Part 12A, the ash is fused with sodium hydroxide and sodium carbonate to bring it into solution. An alternative method in Part 12B uses a microwave-assisted digestion technique with nitric and hydrofluoric acid. The prepared sample is suitable for radionuclide analysis, notably for radio-strontium or plutonium. 

In 1 of these plants, silica is taken up through the roots as dissolved Si(OH)4 and is precipitated within and around the cells as hydrated opaline deposits which often replicate the shapes of the associated cellular structures. Upon death and decomposition of a plant, these siliceous deposits are released to the soil as discrete and generally microscopic structures known as phytoliths or plant opal . Most phytoliths in soils are derived from the aerial parts of plants. However, silicification can be extensive also in the roots and rhizomes of certain grasses, so that soils developed under this kind of vegetation receive significant quantities of biogenic silica from the underground portions of the plants. A rarer type of siliceous deposit in some vascular plants is tabashir (Jones et al., 1966). This material apparently is restricted to the bamboos, where it occurs within the hollow stems as solid, transluscent, opaline masses up to several cm thick. 

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