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The three basic types of ligules are: membranous, a fringe of hairs (ciliate), and absent or lacking. Most grasses have ligules, and the shape, length, and appearance of the ligule margin provide consistent characters for separating genera and some species of grasses. Ligulate floret, typical for flowers of some members of the family Asteraceae:
Symbol used to represent in situ permeability tests in geotechnical drawings. In fluid mechanics, materials science and Earth sciences, the permeability of porous media (often, a rock or soil) is a measure of the ability for fluids (gas or liquid) to flow through the media; it is commonly symbolized as k.
Serpentinite is a meta-igneous rock formed by the metamorphic reaction of olivine-rich rock, peridotite, with water. Serpentinite has a mottled, greenish-gray, or bluish-gray color and is often waxy to the touch. The rock often contains white streaks of chrysotile running through it, which are a type of naturally occurring asbestos.
Phytoliths in grasses, sponges and diatoms are the biogenic sources of silica. Phytoliths usually provide continental source of silica while sponges and diatoms are marine silica sources. Lithological silica are brought to surface through volcanic events whereas weathering of pre-existing rocks releases silica into the waters.
For example, microscopic particles of silica called phytoliths can be found in grasses and other plants. Silica is an amorphous metalloid oxide formed by complex inorganic polymerization processes. This is opposed to the other major biogenic minerals, comprising carbonate and phosphate , which occur in nature as crystalline iono-covalent solids ...
This hyperpolarization of the membrane allowed the accumulation of charged potassium (K +) ions and chloride (Cl −) ions, which in turn, increases the solute concentration causing the water potential to decrease. The negative water potential allows for osmosis to occur in the guard cell, so that water enters, allowing the cell to become turgid.
Parenchyma is a versatile ground tissue that generally constitutes the "filler" tissue in soft parts of plants. It forms, among other things, the cortex (outer region) and pith (central region) of stems, the cortex of roots, the mesophyll of leaves, the pulp of fruits, and the endosperm of seeds.
In geology, a bed is a layer of sediment, sedimentary rock, or volcanic rock "bounded above and below by more or less well-defined bedding surfaces". [1] A bedding surface or bedding plane is respectively a curved surface or plane that visibly separates each successive bed (of the same or different lithology ) from the preceding or following bed.