Gymnosperms (Gr: gymnos: naked, sperma: seeds) refer to those plants whose seeds are naked and not enclosed inside the fruit. In other words, ovary is absent. The gymnosperms are the most ancient seeded plants that originated during late Palezoic era
Characteristics of Gymnosperm:
1.Gymnosperms are sporophyte, woody plants. Annual and herbaceous forms are absent. Most of them are tree.
2. Sporophyte is differentiated into root, stem and leaves.
3. Root is tap root. Roots of some species show symbiotic relation with algae or fungi.
4.Stem is branched. Usually two types of branches are found ;branch of unlimited growth(long shoot) and branch of limited growth (dwarf shoot)
5. Xylem lacks vessel whereas phloem lacks companion cells
6. In most of the gymnosperm, reproductive organs are aggregated in the form of compact cones.
7. Antheridium is absent but archegonium is present.
8. Neck canal cells are absent in archegonium.
9. Pollination is direct.
10. Endosperm which provides food to embryo is haploid and is formed before fertilization.
11. Double fertilization and triple fusion is absent.
12. Seed is naked i.e.not enclosed with in fruits.
13. Polyembryony(occurrence of more than one embryo in a seed) is common.
The members of gymnosperms are categorised on the four orders they are the Cycadales, the Ginkgoales, the Coniferales and the Gentiles. However, Coniferales form is the most conspicuous order of living gymnosperms. Some economically important Gymnosperms are : Pinus, Abies, Juniperus, Cycas etc.