Question

Characteristics of gymnosperms.

Answer 1

The important characteristics of gymnosperms are:

1. Gymnosperms are characterized by the presence of naked ovules which are unprotected and borne on the surface of megasporophyll.
2. They are known as the phanerogams without ovary.
3. Gymnosperms are ever green trees or shrubs with xerophytic adaptations.
4. The plant body is sporophytic and it is differentiated into root, stem and leaves.
5. The plants have a well-developed tap root system.
6. Certain gymnosperm roots possess a symbiotic relationship with algae or fungi. Eg. Coralloid root of Cycas, Mycorrhizal roots of Pinus.
7. The stele in the root may vary from diarch to polyarch condition.
8. The stem is usually erect, branched or unbranched.
9. The presence of leaf scars on the stem is a characteristic feature of gymnosperms.
10. The leaves are dimorphic; the foliage leaves are green, simple and needle like whereas the scale leaves are minute and deciduous.
11. The Anatomy of stem is characterized by the presence of large number of tannin cell.
12. The xylem consists of tracheid and xylem parenchyma but companion cells are absent.
13. The stem shows secondary growth and conspicuous annual rings are present.
14. The gymnosperms are heterosporous; the microspores give rise to male gametophyte and the megaspore give rise to the female gametophyte.
15. Two types of cones or strobili are borne on the same tree (Pinus) or on the different tree (Cycas).
16. The development of sporangium in the gymnosperm is usually eusporangiate.
17. Presence of resin canals in the secondary wood of number of gymnosperms.
18. Most of the members possess non-motile male gametes.
19. The ovules are orthotropous and unitegmic but bitegmic in gnetales.
20. Pollination occurs by wind.
21. The naked ovule develop into seed; the ovular integument forms the seed coat.
22. The gymnosperms have distinct alternation of generation between the sporophytic generation and gametophytic generation. The diploid sporophytic generation is the dominant where the gametophytic phase is dependent on the sporophyte.