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
Philodendron cells that line the sclerotic hypodermis are elongated and tend to be hardened. Underneath the epidermis is a unique layer of cells in a pattern of long cells followed by short cells. Some philodendrons have extrafloral nectaries (nectar-producing glands found outside of the flowers). The nectar attracts ants, with which the plant enjoys a protective symbiotic relationship. Nectaries can be found in a variety of locations on the plant, including the stalks, sheaths, lower surfaces of the leaves, and spathes. The nectaries produce a sweet, sticky substance the ants like to eat and which provides an incentive for them to