The largest phylum grouping in the plant kingdom is angiospermophyta, which contains at least 300,000 species. Species within this phylum all undergo a common mode of reproduction wherein a plant makes flowers which consequently develop into fruits with seeds.
The bryophyte (15,000 species), filicinophyta (11,000 species) and lycopodophyta (1,000 species) groupings follow the angiospermophyta as the second to fourth largest groupings numerically. The remainder of the phyla classes contain somewhere from one to 600 species.
The term angiospermophyta receives its name from three Greek root words meaning a box (angos), a seed (sperma) and a plant (phyto). As the name demonstrates, this phylum is characterized by enclosed seeds in flowering plants. This phylum is largest in number likely because species from this phylum can occur in almost all the freshwater and terrestrial environments on earth. The phylum also contains a wide variety, with plants ranging from nearly microscopic to enormous trees such as oaks.