Photosynthesisis the process by which plants use energy from the sun to convert water and carbon dioxide into sugar and release oxygen into the atmosphere.Criteria for plant classificationis based on features like: does the plant have distinct parts like stem, roots and leaves, do these parts have tissues that transport food and water, does the plant bear naked seeds and are these seeds enclosed in fruits.Eichler classified the plant kingdom into two sub-kingdoms Cryptogamae and Phanerogamae.Cryptogamaeincludes plants with hidden reproductive organs and plants do not bear flowers or seeds.Thallophyta are the simplest of plants that do not have a well-differentiated body design.Algae do not have leaves, stems or roots.Bryophyta are often called amphibians of the plant kingdom as they require both aquatic and terrestrial conditions for the completion of their
life cycle. Moss or Funaria belongs to the group Bryophyta.Bryophyta include Riccia and Marchantia. Pteridophyta include fern plants, in which the plant body is differentiated into stem, leaves and roots and also have naked embryos in the form of spores underneath the leaf.All plants that develop seeds and have well-formed stem, leaves and roots, belong to the sub-kingdom Phanerogamae.Gymnosperms include the plants with naked seeds.Angiosperms include the plants with flowers and seeds enclosed in fruits.Embryos in these seeds have 'seed leaves' called cotyledons. Cotyledons supply food to the growing embryos, when the seeds germinate.An amazing variety of flora and fauna are included in the chart-classification of plant kingdom.Differences between monocots and dicots plants includes the variation in seed, root and in leaves.
Members of the plant kingdom are called Plantae; they are set apart from other organisms by two unique characteristics: they are all eukaryotes, and use chlorophyll for photosynthesis to make their own food.
Cryptogams are further divided into three groups: Thallophyta, Bryophyta and Pteridophyta.
Phanerogams are further classified into Gymnosperms and Angiosperms.
Algae are mostly aquatic, and are autotrophic in nutrition. Examples of algae included in Thallophyta are chlamydomonas, spirogyra, ulothrix, cladophora and chara.
Bryophytes are plants that usually grow in damp, humid and shaded localities. The moss you see on walls, rocks and barks of trees are included in bryophytes. Their body is differentiated to form stem and leaf-like structures, but not true leaves and roots. Vascular tissues, which are special tissues for the transportation of nutrients and water, are absent in Bryophytes.
Pteridophytes were the first terrestrial plants to possess vascular tissues – xylem and phloem. Pteridophytes are plants that flourish in a damp, cool and shady habitat, although some species also grow in sandy-soil conditions.
Gymnosperms were the first plants to have a seed habit. Gymnosperms get their name from two Greek words: gymno – meaning naked, and sperma – meaning seed. Pinus, cycas and other coniferous trees are Gymnosperms. In these plants, the ovules are not enclosed by an ovary wall, but remain exposed or naked.
The word ‘angiosperm’ means ‘covered seed’. Angiosperms are highly evolved plants with flowers, fruits and seeds; they are also called flowering plants. In these plants, the seed germinates and the embryo develops into a new plant.
Angiosperms are divided into two groups, namely, monocots and dicots, based on the number of cotyledons that they have.
Plants with seeds having one embryonic seed leaf or cotyledon are called monocots, while those having two seed leaves or cotyledons are called dicots. Corn seed is a monocot and, bean seed is a dicot.
The leaves of a monocot plant have parallel venation, while that of a dicot plant have reticulate venation.
In monocots, the primary root perishes quite early and gets replaced by a cluster of adventitious roots, whereas in dicots, the primary root becomes the most prominent root of the plant, called the tap root, from which several lateral roots branch out.