Angiosperms are mainly plants that produces flowers and produce fruits as its product . They are many flowers that we even eat , we don’t know much about angiosperms yet but we are about to . In this article i am going to discuss about the general features of Angiosperms so let’s get started .
What are Angiosperms
Angiosperms (Greek word-Angio=Vessel/Case, Sperma=Seed)
Firstly note down some important terms which are very useful for your understanding the differentiation between different terms often used in test books in Angiosperms and other plant groups.
1. Microspore Mother Cell/Pollen Mother Cell (PMC) – diploid (2n) cells
2. Megaspore Mother Cell (MMC) – diploid (2n) cells
3. Microsporophyll=Stamen
4. Megasporophyll=Carpel/Pistil
5. Male-Gametophyte=Pollen Grain
6. Female-Gametophyte=Emryosac
7. Megasporangium=Ovule
8. Microsporanguim=Anther
9.Microspore-haploid(n) cells
10.Megaspore-haploid(n) cells
11.pollen grain with two cells- smaller Generative cell & larger Vegetative cell
12.Embrosac with 7 cells & 8 Nuclei Stages
Main Features of Angiosperms
-First plants in which Flowers and Fruits are evolved.
-First plants in which Ovary is present.
-First plants in which seed is not naked and covered by fruits.
-They are the most advanced plants in plant kingdom.
-Main plant body is Sporophyte while Gametophyte (Pollen grain & Embryosac) is highly reduced and totally dependent on parent Sporophytic plant.
-They are also known as F5-Plants (Flower, Fruit, Fooder, Fuels & Food)
-Size may be very small as Wolfia(0.1 cm) or very large size as Eucalyptus(100 mt tall).
-Life cycle pattern of Angiosperms is Diplontic.
-Angiosperms divided into main classes namely –
i- Monocotyledenae (Monocot) represents 50000 species-plants produce seeds with single cotyledon & parallel venation in leaf.
ii- Dicotyledenae (Dicot) represents 220000 species- plants produce seeds with two cotyledons & reticulate venation in leaf.
–Flowers are the most Unique features in Angiosperms and has four whorls or floral appendages, the outer two whorls is known as accessory whorls represents calyx (sepal) & corolla (petals) and not involves directly in reproduction while inner whorls Androecium and Gynoecium (stamen & carpel)represents essentials part and means of reproduction
-Flowers are the means of sexual reproduction and have male & female reproductive organs.
-Male reproductive organs is called Stamen (or collectively called as Androecium).
-Female reproductive organs is called Carpel/Pistil (or collectively called as Gynoecium)
-Main plant body is Saprophytic which diploid (2n) and produce haploid spores after meiosis.
-All Angiosperms are heterosporous hence produce two kinds of spores smaller one is called microspore & larger one is called megaspore.
-haploid(n) Microspores develop in microsporangium located in stamen.
– haploid(n)Megaspores develop in megasporangium located in pistil/stamen.
– Microspores develop from diploid(2n) Microspore Mother Cell/Pollen Mother Cell(PMC) after meiosis in microsporangium located anther
-Microspore later develops into male gametophyte or Pollen grain.
-In 60% angiosperms pollen grain shed at two cell stages (larger cell-vegetative cell & smaller cell-generative cell ) .
– Megaspores develop from diploid(2n) Mega Mother cell(MMC) after meiosis in megasporangium which is located in ovule of carpel.
-Megaspore after three round of mitosis division develops on female gametophyte or embryosac.
-Embryosac has 7 cells & 8 Nuclei stages(3 Antipodal cells with three nucleus at chalazal end, two synergid cells with two nucleus & one egg cell with one nucleus at micropylar end & one largest cell of Embryosac is Central cell with two polar nuclei)
-Hence Combinations of cell is = 3+1+3 & Combinations of Nuclei is = 3+2+3
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