The original plant kingdom proposed by Linnaeus and subsequent taxonomists of that period included the bacteria, fungi, algae, liverworts, mosses, ferns, conifers and flowering plants. Plants in general are considered to exhibit the following distinguishing characters.
* Plants exhibit a great deal of variation in their form and size. Plant body is usually asymmetrical. However, in higher plants structures like leaves and flowers have a definite form and shape.
* Plants are rooted mostly and as such are incapable of locomotion. However, certain localized movements may occur in a plant body.
* Plants exhibit unlimited growth, almost throughout their life span.
* Absence of locomotion.
* Plants exhibit largely autotrophic nutrition or saprotrophic nutrition. Particulate matter cannot be absorbed and only materials present in a solution state can be absorbed.
* Plant body is composed of cells which have a distinct cell wall, a vacuole filled with sap and plastids of different kinds. The cells do not have centrioles and lysosomes.
* Plant cells can synthesize all the amino acids, coenzymes and vitamins necessary for its functions.
* Plants have reserve food as starch.