In the plant kingdom, the position of gymnosperms is occupied between pteridophytes and angiosperms, as they have a close affinity with pteridophytes on one hand and with angiosperms on the other. The plant groups that bear naked seeds are called gymnosperms. So far, a total of 63 genera and 722 living species constitute the gymnosperms. The term “gymno” means naked, and “sperm” means seed. However, the description provided seems to be slightly incorrect regarding the sub-division Gymnospermae. Gymnosperms are characterized by having their seeds exposed on the megasporophylls, but they do not have carpels like angiosperms. Instead, the sub-division Gymnospermae includes all autotrophic green plants that have exposed seeds on their megasporophylls.
How gymnosperms are differ from angiosperms-
The following reasons are considered for how gymnosperms are different from angiosperms or not advanced –
- Vegetative means of reproduction by means of cuttings, layering, etc. are absent in gymnosperms.
- Their growth rate is slow and dispersal of spores take place only by means of wind or by human being.
- Xylem vessels are absent except Gnetum, campanion cells absent in phloem.
- As the flowers are unisexual, hence chances of self-fertilization is reduced, lots of pollen grains are wasted due to wind pollination
- The ovules and seeds are naked as no formation of fruit takes place due to the absence of ovary.