Cycads are an ancient group of seedplants characterized by a large crown of compound leaves and a stout trunk . They are evergreen ，gymnospermous ，dioecious plants having large pinnately compound leaves . They are frequently confused with and mistaken for palms or ferns ，but are related to neither ，belonging to the division Cycadophyta .
They have very specialized pollinators and have been reported to fix nitrogen in association with a cyanobacterium living in the roots . This blue-green algae produces a neurotoxin called BMAA that is found in the seeds of cycads .
The cycad in the Shimin Square is seen in beautiful flowers ，which attracts a lot of people’s attention .
没有评论:
发表评论