General Characteristics of gymnosperms

1. Gymnosperms have true roots.

2. Their stems are aerial.

3. Their carpels are not distinguished into stigma, style and ovary.

4. They possess naked seed.
5. Their flowers are always unisexual, simple and without perianth.

6. They are heterosporous (i.e., they produces both megaspores and microspores).
7. They are sporophytic plants.

8. Pollination in them mainly occurs through wind.

9. They are woody, perennial or shrubs.

10. Secondary growth occurs in them.
11. Pollen grain germination leads to the formation of a pollen tube in them.
12. Megasporangium in them is protected by means of integument.
13. Generally xylem in them consists of tracheids and xylem parenchyma.

14. Generally phloem in them consists of phloem sieve tubes and phloem parenchyma.

15. They have two different types of leaves – green foliage leaves and brown scale leaves.

16. Endosperm tissue (i.e., Prothallial tissue) formation in them usually occurs before fertilisation.

Examples: Cycas, pinus, Ginkgo, Gnetum, Abies, etc.

Classifications:

Class1: Cycadopsida

i) They have monoxylic wood.

ii) Their leaves are large frond-like.

iii) Seeds in them are with radial symmetry.

Class2: Coniferopsida

i) They have pycnoxylic wood.

ii) Their leaves are simple, either paddle-shaped or fan-shaped.

iii) Seeds in them are with bilateral symmetry.

Class3: Gnetopsida

i) Xylem tissue in them consists of tracheids and vessels.

ii) Their leaves are broad elliptical or star-shaped.

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