Various type of classification were given to explain angiosperm as follows:

1. Bentham and Hooker’s system of classification (1862-1883).
2. Engler and Prantl system of classification (1887-1915)
3. Takhtajan system of classification (1959)
4. Cronquist system of classification (1968)
5. Thorne system of classification (1981)
6. In india Bentham and Hooker’s classification of plants is famous and most accepted. We will study about it short here.

Bentham and Hooker’s System of Classification:

George Bentham, a self-trained British Botanist and Sir Joseph Dalton Hooker, Director of the Royal Botanic Gardens, Kew (England), proposed a natural system of classification in their book Genera Plantarum, which includes three volumes containing the description of all known genera of seed plants in Latin. First volume of this book was published ini 862 and last volume in 1883. This system of classification, which is clearly derived from the systems of de Jussieu and de Candolle, is the best and most accepted natural system and is still used and followed in several herbaria of the world, including India.

De Candolle kept Gymnosperms with Dicotyledons while Bentham and Hooker system of classification divided all the Phanerograms or seed plants into Dicotyledons, Gymnosperms and Monocotyledons, with Ranales placed in the beginning of the classification and grasses at the end. They kept Gymnosperms in between Dicotyledons and Moncotyledons. Bentham and Hooker’s classified seeded plants or Phanerogames into three classes on the basis of morphological characters, phyllotaxy, venation, floral whorls-calyx, corolla, androecium, gynoecium, seed coat and number of cotyledons in plants.-Dicotyledons, Gymnosperm and Monocotyledons.

Class I: Dicotvledonae
Main characters of this class are: Two cotyledons in seed with embryo. Tap root system present. Open and ring type of vascular bundles (conjoint, collateral, endarch vascular bundles). Reticulate venation in leaves. Pentamerous or tetramerous flower. Dicotyledonae divided into three subclasses:

1. Polypetalae:

The flowers contain distinct non-essential whorls calyx and corolla. In the corolla petals are free. This sub-class includes 3 series:Thalamiflorae, Disciflorae and Calyciflorae.

• Series Thalamiflorae: Many stamens in the androecium. Flower is hypogynous.
• Series Disciflorae: Hypogynous flowers with a cushion-like disc around or below the ovary.
• Series Calyciflorae: Flowers epigynous or perigynous. Thalamus is in the form of a cup.

2. Gamopetalae:

Flowers with distinct calyx and corolla. In the corolla petals are fused. This sub-class includes 3 serieslnferae, Heteromerae, Bicarpellatae.

• Series Inferae: Flowers with inferior ovary.
• Series Heteromerae: Flowers with superior ovary. Number of carpels – more than two.
• Series Bicarpeilatae: Flowers with superior ovary. Number of carpels – two.

3. Monochlamydeae:

The flowers are with only one non-essential whorl (perianth) or absence of non-essential whorls, o It includes 8 series.

• Curvembryae: Usually single ovule, embryo coiled around the endosperm.
• Multiovulate Aquaticae: Aquatic plants with syncarpous ovary and many ovules.
• Multiovulate Terrestris: Terrestrial plants with syncarpous ovary and many ovules.
• Microembryae: Only one ovule, small, tiny embryo endospermic seed.
• Daphnales: Only one carpel and single ovule.
• Achlamydosporae: Ovary inferior, 1 to 3 ovules – unilocular.
• Unisexuales: Flower unisexual, perianth usually absent.
• Ordines Anomali(Anomolous families): Plants with uncertain systematic position but closer to unisexuales.

Class II: Monocotvledonae:

This group includes angiosperms in which the seed bears only one cotyledon.The leaves are simple and exhibit parallel venation. Closed type of vascular bundles because cambium is absent in it. Vascular bundles are scattered in parenchyma. Flowers are usually trimerous. Roots are adventitious.It is divided into the following seven series.

1. Microspermae: Ovary is inferior; seeds are minute and non-endospermic.
2. Epigynae: Ovary inferior, seeds are large and endospermic.
3.  Coronarieae: Ovary superior, perianth petalloid.
4. Calycinae: Ovary superior, perianth sepalloid.
5. Nudiflorae: Perianth reduced or absent. Seeds are endospermic.
6. Apocarpae: Carpels more than one, free, seeds are endospermic.
7. Glumaceae: Perianth reduced or absent, scaly bracts present.

Class III: Gvmnospermae

Gymnosperms are kept between Dicotyledons and Monocotyledons class.Reproductive structures in this group are in the form of male and female cones.Ovule or seed in this group are naked means ovary or fruit absent in it.
It is divided into three families

1. Cycadaceae
2. Coniferae
3. Gnetaceae