They are shrub or trees. The trees are rdsinous. Stern has central pith. Vascular bundles are present in rings. Secondar) growth occurs due to cambium. Leaves are needle like. They form cones. Ovule is naked. It is not covered by ovary. Pollination occurs through direct contacts. It has three orders:F
I. Order Gnetaceae
- Order Coniferae
- Order Cycadaeeae
Classification system of Wilhelm Eichler
Wilhelm Eichler introduced the phylogenetic trend in the classification. Its major divisions are still lb’lowed. His classification system has following scheme:
These are non- seed producing plants. It has three divisions:
I. Division Thallophyta: They have thallus body. They do not
develop embryo. It has to classes
- Class Algae
- Class Fungi.
2. Division Bryophyta: ‘Hwy have thallus or plant like hod). “Hie) develop embryo. Gametoph)te generation is dominant in them. It has two classes
- Class Hepaticeae
- Class Muse’
3. Division Pteridophyta: ‘Filey are lower vascular plants. They have sporophyte generation dominant. Ii has three classes:
- Lycopod ineae
-These are seed producing vascular plants. They have dominant saprophyte generation. It has two divisions:
I. Division Gymnosperms: They are seed producing nonflowering plants.
2. Division Angiospermae: They are seed producing flowering plants. It has two classes:
Dicotyleae: It has two subclasses: Chlroipetalae and Sympetalae
Classification System of Engler and Prantle
Adolph Engler and Karl Prantle were two German botanists. They published their classification system. They followed the classification system of Eichler. Their system replaced the classification system of Bentham and Hooker. This system dominates in the plant taxonomy now.
Characteristics of this system
I. This system organized the plants according to their affinities and phylogenetic relationships.
It follows systematic plan. ‘Hie plants are arranged from simple to complex one.
According to this system. most primitive flowering plants are without perianth.
The gamopetalous condition is taken as inure advance than polypetalous.
The monocoty ledons are placed before the Dicotyledons.
.6. According to this ‘sy stem. evolution occurs from hypogyny to epigyny. The perigyny condition is intermediate between these tw 0.
Division Embryophyta Siphonogama (Spermatophytes)
These are seed producing plants. These plants are divided into two SU hdiv is ions.
(a) Subdivision Gymnospermae: ‘these naked seeded plants. These •plants are further divided into follow Mc major classes:
I. Class Cycada les
- Class Bennett tales
- Class Ginkgoales
- Class Con i !Crates S. Class Cordaitales
6. Class Gnetales
(b) Subdivision Angiospermae: These seed producing flowering . plants. Their seed is covered by fruits. It is further divided in to two classes:
I. Class Monocotyledonae: These plants have single cotyledons.
They are without pith and cambium. Their leaves have parallel venations. This class is further divided into following main orders:
2. Class Dicotyledonae: ‘these plants have two cotyledons. They develop pith and cambium. Their leaves have reticulate venation. This class is further di% ided into follow ing orders: