Soil plant atmosphere continuum Soil plant atmosphere continuum The soil-plant-atmosphere continuum (SPAC) is the pathway for water moving from soil through plants to the atmosphere. Continuum in the description highlights the continuous nature of water connection through the pathway. The low water potential of the atmosphere, and relatively higher (i.e. less negative) water potential inside leaves, leads to a diffusion gradient across the stomatal pores of leaves, drawing water out of the leaves as vapour. As water vapour transpires out of the leaf, further water molecules evaporate off the surface of mesophyll cells to replace the lost molecules since water in the air inside
Glossary of plant morphology from roots to overhead structures, for water and other growth-enhancing substances. These conduits consist of specialised tissues known as vascular bundles, which give the name "vascular plants" to the angiosperms. The point of insertion, on the stem, of leaves or buds is a node, and the space between two successive nodes, an internode. The leaves, which emerge from the shoot, are specialised structures that carry out photosynthesis, and gas (oxygen and carbon dioxide) and water exchange. They are sheathed by an outer layer or epidermis that is coated with a waxy waterproof protective layer, which is punctuated by specialised pores,