CYCADS AND ZAMIAS.

 

Zamia is a genus within the lineage of the Cycads, a group of tropical Gimnosperms. The species of Zamia belong to the botanical Family Zamiaceae, that with Cycadaceae conform the Order Cycadales, commonly known as “Cycads”. Cycads are Gymnosperms (Gimnospermae), which produce pollen and seeds in cones. Current Cycads are distributed in tropical and subtropical regions of the world, while another Gymnosperms are mostly in temperate zones. 

 

Cycads are an ancient lineage within the seed plants, considered as "living fossils".  Among seed plants (Gymnosperms and Angiosperms) Cycads are a very ancient lineage. Cycads appear in the fossil record in the Permian, towards the en dof the Paleozoic era (more than 200 millions of years ago). During the Mesozoic era, Cycads were dominant plants in ecoysystems, together with Dinosaurs. Most of Mesozoic seed plants are extinct, but some Cycads have remained in tropical ecosystems until our time. In addition to being living fossils, Cycads have many unique characters, that make them very interesting among seed plants. Therefore, Cycads represent an invaluable lineage of plants that warrant important conservation efforts.

 

Cycads are a diverse Gymnosperm lineage. Currently, there are 340 known Cycads species, belonging to 10 genera and 2 families. Cycads exhibit great species richness in countries like Australia (77 spp), Mexico (56 spp), South Africa (38 spp), China (23 spp), Colombia (21 spp) and Panama (17 spp). These species of Cycads include arborescent, herbaceous and even epiphytes forms. Cycads occur from deserts and savannas, to mountains and tropical forest ecosystems worlwide.

 

Cycads have great value as ornamental plants. In countries like Australia, South Africa, China, Mexico and USA, Cycads have an important status in horticulture. In some regions, Cycads have traditional uses by the human populations, who used them as food, medicine, among others. Unfortunately, these traditional uses and the horticulture interest for Cycads have generated an illegal trade, and in some cases this trade has resulted in serious threats for species survival.

 

Cycads are among the most endangered groups of organisms globally. The IUCN Red list for threated species has evaluated several groups of organisms at the global level. According to these evaluations, Cycads are one of the most threatened organisms in the world, with more that 60% of their species listed as in risk of extinction. The main threat for Cycad species is habitat destruction and degradation, and in some cases overexploitation of populations for trade. Because of this, Cycads have become a very charismatic group of plants for biodiversity conservation globally.

 

 

Interesting links about Cycad biology and conservation:


http://cycadlist.org/

http://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/

http://www.cycadgroup.org/

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gallery/mexico2005-d. merolae at las minas
gallery/mexico2005-d. sp oaxacaensis at san jeronimo taviche
gallery/mbc- ripe cone
gallery/mbc- encephalartos with seed
gallery/safrica- encephalartos_horridus