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Cycas – Wikipedia

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**1. Distribution and Species Diversity:**
– Cycas is a genus native to the Old World.
– Species are concentrated around equatorial regions in Asia, Africa, Australia, Polynesia, and Micronesia.
– Australia has 26 species, Indo-Chinese area has about 30 species, and India has 9 species.

**2. Evolution and Fossil Records:**
– Cycas has a deep split from other living cycads.
– The split is estimated to have occurred from the Jurassic to Carboniferous periods.
– Fossil seeds from the Middle Jurassic suggest a relation to Cycas.
– Earliest Cycas fossils are known from the Paleogene of East Asia.

**3. Morphology and Reproduction:**
– Cycas plants are dioecious.
– They do not form seed cones on female plants.
– The caudex is cylindrical with persistent petiole bases.
– There are two types of leaves: foliage leaves and scaly leaves.
– Megasporophylls are not gathered in cones, and pollination occurs by air.
– Cycas takes about 10 years to reach sexual maturity and growth occurs by bulbils at the base of the trunk.
– Male and female cones are present in different species, and pollination also occurs by air.

**4. Conservation Status:**
– Cycas species are threatened worldwide, with almost all species listed on the IUCN Red List.
– Cycas beddomei is listed in CITES Appendix I, and other Cycadaceae members are listed under Appendix II.
– Some species like Cycas rumphii and Cycas pectinata have a widespread distribution.

**5. Notable Researchers and Publications:**
– David de Laubenfels specializes in Cycas taxonomy.
– Hill, Stevenson, and Osborne compiled The World List of Cycads.
– Singh and Khuraijam focus on Cycads of India, while Singh and Radha discovered new species and combinations in India.
– Walters and Osborne’s book ‘Cycad Classification’ presents concepts and recommendations in the field.
– Various journals like Blumea, Botanical Review, Telopea, Asian Journal of Conservation Biology, and Brittonia have published research on Cycas and related species.

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