Rapid plant movement slower "growth-movements" of plants, called tropisms. Tropisms encompass movements that lead to physical, permanent alterations of the plant while rapid plant movements are usually reversible or occur at over a shorter span of time. A variety of mechanisms are utilized by plants in order to achieve these fast movements. Extremely fast movements such as the explosive spore dispersal techniques of "Sphagnum" mosses may involve increasing internal pressure via dehydration, causing a sudden propulsion of spores up or through the rapid opening of the "flower" opening triggered by insect pollination. Fast movement can also be expressed in predatory plants, where the
Types of plant oils means of extracting essential oils. In this process, used, for example, to extract the onion, garlic, wintergreen and bitter almond essential oil, the plant material is macerated in warm water to release the volatile compounds in the plant. Types of plant oils Plant oils or vegetable oils are oils derived from plant sources, as opposed to animal fats or petroleum. There are three primary types of plant oil, differing both the means of extracting the relevant parts of the plant, and in the nature of the resulting oil: Vegetable fats and oils are what are most commonly called vegetable oils.