The kingdom Plantae consists of a diverse and varied group of plants that have been discovered and classified till date. It includes trees, shrubs, conifers and even moss. This group is further subdivided into Angiosperms, gymnosperms, pteridophytes, bryophytes and algae. This classification has been done based on external and internal features such as morphology, anatomy, structure, phytochemistry and so on.
Hence, considering the vast scope of this topic, we will limit our discussion to angiosperms only.
So, What is Angiosperms?
Angiosperms are a type of vascular plant that bear both flowers and fruits. These types of plants also contain ovules enclosed in an ovary. The ovule, once fertilised, develops into seeds which then mature into fruits.
The flowers in plants of these species help in pollination and protect the ovaries and the embryos whereas fruits aid in seed dispersal.
The characteristics of flowering plants or angiosperms that sets it apart from gymnosperms are four sets of organs. These organs are –
The diagram below illustrates each of these parts of a flower –
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According to fossil evidence, this species was first seen during the lower cretaceous period, and it started to evolve rapidly by the middle cretaceous period. It is one of the most diverse groups among the others within the plant kingdom.
One can find angiogram plants ranging from small flowering plants to huge woody trees such as mountain ash trees. However, angiosperm plants belong to two groups which are discussed below.
Classification of Angiosperms
The two major classifications of angiosperms are done based on the number of leaves on cotyledons. They are –
Monocotyledons – The zygote has one embryonic leaf.
Dicotyledons – Cotyledons with two leaf cotyledons.
The function of the cotyledons is to move food from the food storage area to the developing embryo.
Features of Monocotyledons
The following are the salient features of angiosperms which have monocotyledons –
Roots are adventitious and have no primary taproots.
The veins of these plants are parallel to the length of the leaves.
The flower petals are arranged as three or six-fold.
Usually, the trunks or stems of angiosperm plants are made from vascular and parenchyma tissues.
Lilies, orchids, grasses etc. fall under this category.
Features of Dicots
The general features of angiosperms which are dicots are as follows –
Eudicots or dicots can have either woody tissues or can be herbaceous.
The roots have one primary root that develops from the radicle.
Flower parts can have many whorls and veins in leaves form a network.
Importance of Angiosperms
Angiosperms are very important to animals as well as humans.Besides being a significant source of food, they are also crucial from a financial point of view. Economic importance of angiosperms includes
They provide herbs and spices
Trees which are angiosperms are a significant source of timber.
Natural fibre and dyes are sourced from flowering plants.
Reproduction in Flowering Plants
Apart from knowing what angiosperm plants, you should also know how they reproduce. One of the significant differences between angiosperms and gymnosperms are that while the former carries out asexual reproduction, the latter is capable of sexual reproduction.
A characteristic of Angiosperms is that they are heterosporous, which means that they generate microspores and megaspores. The microspores, in turn, create pollen grains containing male gametophytes. The megaspores also develop to form ovules containing female gametophytes.
There are two calls in a single pollen grain – one cell that develops into a pollen tube cell and another is a generative cell that is divided into two sperms.
There is one egg cell, two helper cells, two polar nuclei and three antipodal cells in the female gametophyte. As the pollen grain reaches the stigma, it extends a tube which goes down the style and enters the ovule through the micropyle and deposits two sperm cells in the sac.
It results in double fertilisation. The eggs combine with the sperm to form a zygote or future embryo. The other sperm unites with the polar nuclei to form endosperm, which will act as a food source.
As the zygote develops, a small root called radicle, and leaf-like organs called cotyledons appear. The leaf-like organs can be either one or two in number.
You can go through the articles on this topic on Vedantu’s online portal to learn in detail about the reproductive process in flowering plants. Also, master the study materials by Vedantu to know more about the importance of angiosperms.
1. What are the Two Major Groups of Angiosperms?
Ans. The two major groups of Angiosperms are monocotyledons and dicotyledons.
2. What are Angiosperms?
Ans. Angiosperms are flowering plant species which have specially developed reproductive parts to protect their seeds. One of the general characteristics of angiosperms is that plants belonging to this group have specialised vascular tissue to carry out essential functions such as photosynthesis, nutrition.
3. What is a Characteristic Feature of an Angiosperm?
Ans. One of the features of angiosperms or flowering plants is that they rely on animals for the pollination process.
4. What is the Definition of Angiosperm?
Ans. Angiosperms can be defined as flowering and fruit-bearing plants which have specially evolved reproductive organs.