Cycad

Cycad is a term that refers to a group of cone-bearing plants that are considered living fossils. Actual fossils of such plants are dated by radiometric dating to have an age of supposedly 240 million years. These unique plants remain largely unchanged since plants like them were fossilized. In the modern world, most species are endangered and some are now even extinct. The sago palm is the most well known cycad.

Anatomy
Most cycads have wide, short trunks and frond-like leaves. The trunks can live underground or above ground. The leaves of the cycads contain poisonous chemicals and if the plant is used for food, which it often is, then these chemicals must be removed. The cycads also contain one or more cones. Roots called coralloids form near the surface of the soil and contain a type of bacteria which fixes nitrogen for the plant and in turn helps the plant create its own fertilizer. This nitrogen-fixing ability allows the cycad to grow in very poor soil and establish a competitive ecological niche.

Reproduction
Cycads can reproduce via asexual or sexual reproduction. When it comes to asexual reproduction the Cycads produce stem offshoots or pups. For sexual reproduction cycads are dioecious, which means plants are either male or female. The reproductive structure is specifically called a strobilus or cone. This is a group of leaves which bear either pollen or ovules which become seeds after fertilization. There is a visual difference between the males and females, males are more slender and possesses smaller sporophylls while females are larger and have fewer sporophylls.

Ecology
Cycads are long living and slow growing. Their stems are highly susceptible to fungal attack. Cycads grow well in well-drained soils, making most Cycads' habitat that of a tropical or subtropical climate in regions with summer rainfall. They are found on every continent except Europe and Antarctica. The seeds of cycads are large and brightly colored, including the colors red, purple, and yellow. The colors attract birds and a variety of mammals which disperse the seeds.

Related References

 * Cycad Cycad Identification
 * wikipedia Wikipedia
 * Cycad History of the Cycad