Plant Vascular Processes and Transport Mechanisms

Vocabulary terms and definitions detailing plant transport mechanisms, vascular tissue functions, water movement theories, and agricultural modifications.

Asexual plant reproduction

Also vegetative propagation produces a clone or an organism that is genetically identical to the parent plant

Osmosis

Cells that require large amounts of sugars, typically consisting of rapidly dividing meristematic tissue or storage structures such as roots and fruits.

Pressure-flow hypothesis

The explanation of phloem sap movement stating that active transport of sugars creates high pressure near sources and low pressure near sinks, causing water and dissolved sugars to flow down the pressure gradient.

Phloem

The vascular tissue that transports sugars and other nourishment upward or downward from sources to sinks throughout a plant.

Xylem

The vascular tissue that moves sap consisting primarily of water and dissolved minerals from the soil unidirectionally upward.

Sap

The fluid transported within a plant's vascular tissues, specifically referring to the solutions flowing inside the xylem and phloem.

Cohesion

The tendency of substances to stick together, caused in water by strong hydrogen bonds between adjacent molecules.

Adhesion

An attraction between molecules of different substances, such as water molecules sticking to the walls of a tube or glass.

Capillary action

The movement of a liquid upward against gravity inside a thin tube due to adhesion and cohesion, occurring to a greater degree in thinner tubes.

Cohesion-tension theory

The theory that water is pulled upward through the xylem as transpiration occurs, using cohesion among water molecules to draw water continuously from the roots to the leaves.

Transpiration

The process where water molecules exit the spongy mesophyll of leaves as water vapor through the stomata into the atmosphere.

Turgor pressure

The pressure maintained when water fills a plant cell's central vacuole and pushes the cytoplasm and cell membrane firmly against the cell wall, giving rigidity to the plant.

Root pressure

The upward pushing force exerted on water and dissolved minerals in the xylem, generated by osmotic movement of water into the root cortex following the active transport of minerals.

Endodermis

The cellular root layer through which water is filtered as it travels from the cortex into the xylem.

Hyperion

A coast redwood in California's Redwood National Park that stands just over $116\,\text{m}$ tall, regarded by scientists as the tallest tree in the world.

Glyphosate

A weed killer to which certain genetically modified crops are engineered to be resistant, though several weed species have developed resistance to it.