Entomology The study of insects and their environments. Evergreen tree A tree that retains some or most of its leaves, or needles, throughout the year. Ewe A female sheep of any age. Exotic species A non-native plant or animal species introduced by humans, either deliberately or accidentally. Ecology The study of the mutual relations between organism and their environment. Edaphic factors Soil factors. Electrical conductivity (EC) The property of a substance to transfer an electrical charge (reciprocal of resistance) used for the measurement of the salt of an extract from a soil when saturated with water. Measured in milli mhos/cm or dsm-1 at 25 Degree C. Emasculation The artificial removal of anthers from an immature bisexual flower. Epinasty The twisting and curling of leaves and stem caused by uneven growth of cells. Evaporation Evaporation is the term used to describe the process wherein moisture escapes in the form of vapour from a free water/moist soil surface by the effect of sunlight. Exotic (plant) A newly introduced plant not native to a place.