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Aerenchyma in stem cross section of a typical wetland plant. Aerenchyma or aeriferous parenchyma [1] or lacunae, is a modification of the parenchyma to form a spongy tissue that creates spaces or air channels in the leaves, stems and roots of some plants, which allows exchange of gases between the shoot and the root. [2]
These plants have very deep roots that are able to reach the water table. Phreatophytes are not only characteristic of arid or desert zones, but also of wetlands, floodplains, depressions that hold water and estuaries. In the wetlands, ecological classification does not provide a special classification, since in this case, most of the plants in ...
Water is the chemical substance with chemical formula H 2 O; one molecule of water has two hydrogen atoms covalently bonded to a single oxygen atom. [26] Water is a tasteless, odorless liquid at ambient temperature and pressure. Liquid water has weak absorption bands at wavelengths of around 750 nm which cause it to appear to have a blue color. [4]
The resulting surface tension causes a negative pressure or tension in the xylem that pulls the water from the roots and soil. [citation needed] Root pressure: If the water potential of the root cells is more negative than that of the soil, usually due to high concentrations of solute, water can move by osmosis into the root from the soil. This ...
The corresponding eigenvalue, characteristic value, or characteristic root is the multiplying factor (possibly negative). Geometrically, vectors are multi-dimensional quantities with magnitude and direction, often pictured as arrows. A linear transformation rotates, stretches, or shears the vectors upon which it acts. A linear transformation's ...
These plants have subterranean or under water resting buds, and are divided into: Geophytes: rest in dry soil as a rhizome, bulb, corm, et cetera, e.g. crocus and tulip, and are subdivided into: Rhizome geophytes, Stem-tuber geophytes, Root-tuber geophytes, Bulb geophytes, and; Root geophytes.
A fine root is most commonly defined as a plant root that is two millimeters or less in diameter. [1] Fine roots may function in acquisition of soil resources (eg. nutrients, water) and/or resource transport, making them functionally most analogous to the leaves and twigs in a plant's shoot system. [1]
Hydrotropism (hydro- "water"; tropism "involuntary orientation by an organism, that involves turning or curving as a positive or negative response to a stimulus") [1] is a plant's growth response in which the direction of growth is determined by a stimulus or gradient in water concentration.