Gymnosperms are small group of plants which act as connecting link between pteridophytes and angiosperm. Gymnosperms are classified into four classes;Cycadophyta, ginkophyta, gnetophyta, coniferophyta.
Algae are eukaryotic organisms which are not differentiated into roots, stem and leaves. Algae are thalloid organism which are included in kingdom Plantae. Algae are classified into six classes.
Angiosperms are the largest group of plant on this earth. They grow as trees, shrubs , bushes, herbs and small flower plants. Angiosperms are classified in two classes; Monocot and Dicot.
Pteridophyta are first true land plant that evolved after bryophytes. Hence they are known as amphibians of plant kingdom. Pteridophytes are classified into following four classes; Pterophyta, lycophyta, sphenophyta and psilophyta.