Vacuole
A cellular organelle that is used for the storage of any number of compounds, including food, water and waste.

Vapor pressure deficit
A measure of the "dryness" of the air.  A high vapor pressure deficit corresponds to a low relative humidity and/or high temperature, while a low vapor pressure deficit corresponds to a high relative humidity and/or low air temperature.

Varve
A layer in a deposit of sedimentary material, showing seasonal variation caused by differences in summer and winter deposition.  Varves are particularly characteristic of the layering of sediments carried by glacial meltwater.

Vascular plants
Plants that possess vascular tissue for transporting water, nutrients and plant photosynthetic products.  Xylem cells transport water and minerals from roots to aerial plant parts, while phloem cells transport photosynthetic products from leaves to belowground plant components.

Vernalization
A cold temperature treatment (often lasting 2 to 6 weeks) required by some seedlings to induce reproductive growth.

Vesicle
A small bladder-like sac used by arbuscular mycorrhizal fungi for carbon storage.