Gymnosperms have pollen but no flowers. Pollen is made by the male cones from microspores that come from microsporocytes created during meiosis. Using the wind, the pollen granules pollinate the female cones. Gymnosperms came into existence in the early Mesozoic era about 359 to 299 million years ago. They are the ancestors of the flowering angiosperms that appeared around 145.5 to 65.6 million years ago during the late Mesozoic era.
Over millions of years, early plants developed seeds and pollen as adaptations to drought conditions and this is the origin of gymnosperms. Their ability to reproduce and for embryos to grow without water also paved the way for them to eventually colonize dry land. Before this, fossil evidence shows that certain extinct species of scorpionflies used their proboscises to pollinate extinct progymnosperms (their predecessors) during the middle of the Devonian period from 419.2 to 358.9 million years ago.
As the organisms on the planet evolved and biodiversity exploded, angiosperms came on the scene and evolved flowers to attract bees and other pollinators. They also started to develop fruits to allow animals to help disperse their seeds. Although there are over 260,000 species of angiosperms today compared to about 1,000 species of gymnosperms, the gymnosperms are just as important in the evolutionary history and diversity of the planet.
The image above shows the male (lower) and female cones of the Japanese Cedar tree Cryptomeria japonica.
References
- OpenStax College. (2017). Concepts of Biology. Houston, TX. Open Stax CNX. Retrieved from http://cnx.org/contents/b3c1e1d2-839c-42b0-a314-e119a8aafbdd@9.39