Cycadaceae
Cycadaceae Pers. is monogeneric, containing only the genus Cycas L., with approximately 120–130 species distributed primarily in tropical and subtropical Asia, Australia, and the western Pacific. Molecular phylogenetic studies support the recognition of Cycadaceae as a distinct and ancient lineage of gymnosperms that diverged early in seed plant evolution. Members are characterized by stout unbranched trunks, pinnately compound leaves, and separate male and female reproductive structures. Unlike most other cycads, female plants of Cycas do not produce compact seed cones; instead, ovules are borne on leaf-like megasporophylls.
Key characteristics
- Slow-growing evergreen gymnosperms
- Stout, usually unbranched trunk
- Large pinnately compound leaves in a terminal crown
- Young leaves circinate
- Plants dioecious
- Male reproductive structures cylindrical pollen cones
- Female ovules borne on leaf-like megasporophylls
- Large exposed seeds with fleshy outer coats
Distribution
The family is distributed from South and Southeast Asia through southern China, Japan, Taiwan, the Philippines, Indonesia, New Guinea, northern Australia, and numerous Pacific islands. Species occur in tropical forests, coastal habitats, limestone hills, open woodlands, and seasonally dry environments, ranging from sea level to montane regions. Cycadaceae is not native to Pakistan. Species of Cycas, particularly Cycas revoluta, are widely cultivated as ornamental plants Capital Territory. They are commonly grown in botanical gardens, university campuses, public parks, hotels, and residential landscapes because of their distinctive symmetrical foliage and high ornamental value.