Cycad
| Cycadales Temporal range:
| |
|---|---|
| Cycas rumphii with old and new male strobili | |
| Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Spermatophytes |
| Clade: | Gymnospermae |
| Division: | Cycadophyta Bessey 1907: 321. |
| Class: | Cycadopsida Brongn. |
| Order: | Cycadales Pers. ex Bercht. & J. Presl |
| Extant groupings | |
| Synonyms | |
| |
Cycads /ˈsaɪkædz/—constituting the division Cycadophyta—are seed plants with a stout, woody cylindrical trunk with a crown of large, hard, stiff, evergreen and usually pinnate (feather-shaped) leaves. The species are dioecious, that is, individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall. They typically grow slowly and have long lifespans. They superficially resemble palms or ferns, but are not closely related to either group. Cycads are gymnosperms. Cycads have specialized pollinators, usually a specific beetle, and more rarely a thrips or a moth.
Both male and female cycads bear strobili, somewhat like conifer cones, containing their pollen and seeds, respectively. Cycads fix nitrogen in association with cyanobacteria living in their roots. Some species are used as narcotics, while in Vanuatu the plant symbolizes peace and appears on the national flag. Cycads all over the world are in decline, with four species on the brink of extinction and seven species each with fewer than 100 plants left in the wild.