What are cycads?

Cycads are the order of seeds of seeds, cycadales, known for their strong strains and compound leaves, tropical and subtropical distribution and associations with the mesozoic era and dinosaurs. Before the rise of flowering plants about 80 million years ago, Cycads and their relatives, conifers, dominant plants on the ground were. Cycads are one of the four divisions of gymnosperms (plants non -forming seeds). Other divisions are conifers, ginkgo and gnetophytes. Gymnosperms have "naked seeds" unlike angiosperms whose seeds are protected by Karpl. Cycads are often confused with ferns and palms, even if they are not associated with any.

The development of Cycads was dated with early permin, about 280 million years ago, although there is a possibility that some cycades existed in a carbon, 325 million years ago. They quickly gained worldwide distribution and were located on all major continents that existed at that time. Cycads that are adapted to subtropical and tropical conditions have flourished for the next time200 million years, because the temperature of the planet was banging and quite uniform. It would not be unusual to see Cycads growing in what northern Europe or northern United States is today.

Cycads are unusual in that fossils of pollen showed that they were once much more diverse than today. Unlike the thousands that probably existed, there are only about 305 existing Cycad species. Significant genetic differences between three main surviving Cycad lines also point to their old genetic diversity. Cycads are endemic for their relevant continents - American cycades are different from African cycads, which are different from Southeast Asia Cycads. There is a significant amount of disagreement about how many types of Cycads actually exist, because some different species are able to interlegate and raise questions about the conventional concept of biological species.