Table of Contents
What is a plant kingdom?
A plant kingdom is a taxonomic rank used in the classification of living things. Organisms in a plant kingdom share certain characteristics, such as the presence of cell walls made of cellulose and the ability to carry out photosynthesis.
The Level of Classification is Grounded on the Following Three Criteria:
The level of classification is grounded on the following three criteria:
1. The level of classification should be based on the amount of information that is known about the object.
2. The level of classification should be based on the amount of change that can be expected in the object.
3. The level of classification should be based on the amount of control that can be exercised over the object.
Classification of Plants:
Plants are classified by their physical characteristics and the way they reproduce. The divisions of plants are:
-Plants that produce seeds inside a fruit: these plants are classified as angiosperms.
-Plants that produce seeds on the surface of a fruit: these plants are classified as gymnosperms.
-Plants that produce spores: these plants are classified as bryophytes.
1. Thallophyta
Thallophyta are a group of simple, mostly aquatic, organisms that lack true leaves, roots, and stems. They are distinguished by their lack of differentiation into these organs, and by their production of spores.
2. Bryophyta
Bryophytes are a group of mosses and liverworts. Mosses are small, green plants that grow in clumps on the ground. Liverworts are small, flattened plants that often grow in moist places. Both mosses and liverworts have simple leaves and lack flowers or seeds.
3. Pteridophyta
Pteridophyta, commonly known as ferns, are a group of vascular plants that reproduce via spores and have neither seeds nor flowers. They are distinguished from other plant groups by their unique life cycle, which includes a dominant sporophyte stage. Pteridophytes are distributed worldwide, and are estimated to compose approximately 15% of Earth’s vascular plant diversity.
Characteristics of Pteridophyta
Pteridophytes are vascular plants that have lignified tissues and reproduce by spores. They are generally terrestrial, but some species are aquatic. They have a dominant sporophyte generation and a dominant gametophyte generation. The sporophyte generation is generally taller and has more complex tissues than the gametophyte generation.
4. Gymnosperms
Gymnosperms are a group of plants that have seeds but do not flower. These plants are cone-bearing, and their seeds are not enclosed in a fruit like many flowering plants. The gymnosperms include the conifers, cycads, and ginkgo.
5. Angiosperms
Angiosperms are flowering plants that produce seeds enclosed in an ovary. This group includes familiar plants such as roses, apples, and oak trees.
Classification of Angiosperms
The angiosperms are classified into two major groups: the monocots and the dicots.
The monocots have one cotyledon, or seed leaf, in the embryo of the seed. The dicots have two cotyledons.
The monocots are generally herbaceous plants with leaves that are parallel-veined and have a single vein running the length of the leaf. The dicots are generally woody plants with leaves that are net-veined and have several veins radiating from the leaf stalk.
