Peculiarities of the reproductive processes in the gymnosperms. Gametophytes’ development, pollination and fertilization

Abstract

The review contains the analysis of the latest literature sourses reproductive processes in gymnosperms, namely gametophytes development, рollination, fertilization. The peculiarities of these processes in the various classes of gymnosperms as also differences and similarities with the Angiosperms are noted. It was shown that male and female gametophyte development goes according to the common plan. Deep adaptations for zoophyly were revealed in Cycadopsida and Gnetopsida, and confirmed with paleontological data in fossil Gymnosperms. Anemophyly in Ginkgo and Pinopsida revealed the high specialized pollination mechanisms. The penetration of the male gametophyte to the female after pollination (post-pollinative stage of the reproductive cycle) reveals a great variability as also fertilization process does. The described facts confirm that differences between the classes of Gymnosperms are comparable with the differences between Gymnosperms and Angiosperms. From another side, common adaptive features between all classes of seed plants exist, and they are connected with seed reproduction. Most specific reproductive processes are typical for Gnetopsida. They tetrasporic female gametophyte, absence of archegonia and differentiated egg cells, “double fertilization”.

Keywords

• gymnosperms
• gametophytes
• рollination
• fertilization
• pollen grain
• ovule
• anemophyly
• zoophyly
• post-pollinational phase