The Gymnosperms are most ancient group of seed plants that originated during late Paleozoic Era about 395-359 million years before present . Their long evolutionary history is full of diverse lines of evolution (within the group) during which many morphoforms originated, diversified and disappeared as is known by their fossil history.

Characterstic Features of Gymnosperms

The gymnosperms are a most ancient group of seed plants with a long geological history and exhibit the following characteristic features:

1. There are no aquatic and herbaceous plants in this group.

2. The plants are mostly xerophytes and/ or evergreen , woody arborescent or majestic trees or shrubs and some are lianes.

3. The plant body is a sporophye with root, stem and leaf.

4. The tap root system is well developed and persists for a long time often reaches shallow depths and associated with mycorrhizal fungus.

5. Foliage is dimorphic and comprises of brown scale leaves and green photosynthetic leaves.

6. The shoot system is well developed with extensive branching .

and essentially consists of tracheids and rays with occasional wood-parenchyma . However, vessels are present in Gnetales.

8. The Phloem consists of sieve cells and phloem parechyma.

9. The plant shows extensive development of secondary growth.

10. The flowers are unisexual and the plants are dioecious or monoecious.

11. Micro-and megasporophylls are usually borne in more or less distinct cones.

12. Both male and female cones are greatly reduced. 

 Male gametes are motile or non-motile and the fertilization is 

14. Prothallial cells are formed in the male gametophyte.

15. There is a prolonged nuclear phase in the development of the female gametophyte and a long interval between pollination and fertilization.

16. A free nuclear phase is seen in the development of the 

and occurrence of haploid nutritive tissue in the female gamatophyte.

17. Haploid endosperm is formed before fertilization.

18. Though polyembryony is common, only one embryo attains maturity.

19. Ovules orhotropous with a single integument (

 usually divisible into three layers, the outer and inner 

20. Mature embryo possesses radicle, plumule and many cotyledons.

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