Xerophytes are plants that prefer arid conditions and require little or no irrigation. Hydrophytes are plants that prefer wet conditions Mesophytes are plants that have moderate water requirements. The botanical system is based on the hypothesis that plants evolved from a single, less complex organism and that all plants are more or less distantly related. Plants are usually grouped by their vegetative and reproductive structures. The Flowering Plants are divided into two major classes - the monocots and the dicots .
Monocots are usually non-woody plants that have a short stem and leaves arranged in a rosette.
The leaves are frequently long and narrow, with parallel veins. Underground many monocots form either bulbs or fleshy roots. Their flower parts are found in multiples of three. Whether a plant is a monocot or a dicot can determine its method of propagation and its susceptibility to weed killers. Many similar genera are grouped together into a family .