Cycads/ˈsaɪkædz/ are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate 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 very slowly[3] and live very long. Because of their superficial resemblance, they are sometimes mistaken for palms or ferns, but they are not closely related to either group.
Cycads are gymnosperms (naked-seeded), meaning their unfertilized seeds are open to the air to be directly fertilized by pollination, as contrasted with angiosperms, which have enclosed seeds with more complex fertilization arrangements. Cycads have very specialized pollinators, usually a specific species of beetle. Both male and female cycads bear cones (strobili), somewhat similar to conifer cones.
Cycads have been reported to fix nitrogen in association with various cyanobacteria living in the roots (the "coralloid" roots).[4] These photosynthetic bacteria produce a neurotoxin called BMAA that is found in the seeds of cycads. This neurotoxin may enter a human food chain as the cycad seeds may be eaten directly as a source of flour by humans or by wild or feral animals such as bats, and humans may eat these animals. It is hypothesized that this is a source of some neurological diseases in humans.[5][6] Another defence mechanism against herbivores is the accumulation of toxins in seeds and vegetative tissues; through horizontal gene transfer, cycads have acquired a family of genes (fitD) from a microbial organism, most likely a fungus, which gives them the ability to produce an insecticidal toxin.[7]
Cycads all over the world are in decline, with four species on the brink of extinction and seven species having fewer than 100 plants left in the wild.[8]
^Brongniart, A. (1843). Énumération des genres de plantes cultivées au Muséum d'histoire naturelle de Paris.
^Bessey, C.E. (1907). "A synopsis of plant phyla". Nebraska Univ. Stud. 7: 275–373.
^Dehgan, Bijan (1983). "Propagation and Growth of Cycads—A Conservation Strategy". Proceedings of the Florida State Horticultural Society. 96: 137–139 – via Florida Online Journals.
^Rai AN, Soderback E, Bergman B (2000). "Tansley Review No. 116. Cyanobacterium-Plant Symbioses". The New Phytologist. 147 (3): 449–481. doi:10.1046/j.1469-8137.2000.00720.x. JSTOR 2588831. PMID 33862930.
^Holtcamp, W. (2012). "The emerging science of BMAA: do cyanobacteria contribute to neurodegenerative disease?". Environmental Health Perspectives. 120 (3): a110–a116. doi:10.1289/ehp.120-a110. PMC 3295368. PMID 22382274.
^Cox PA, Davis DA, Mash DC, Metcalf JS, Banack SA (2015). "Dietary exposure to an environmental toxin triggers neurofibrillary tangles and amyloid deposits in the brain". Proceedings of the Royal Society B. 283 (1823): 20152397. doi:10.1098/rspb.2015.2397. PMC 4795023. PMID 26791617.
^Liu, Yang; et al. (2022). "The Cycas genome and the early evolution of seed plants". Nature Plants. 8 (4): 389–401. doi:10.1038/s41477-022-01129-7. PMC 9023351. PMID 35437001.
^Davis, Judi (27 June 2018). "Meet Durban's famous cycad family". South Coast Herald. Retrieved 11 September 2022.
Cycads /ˈsaɪkædz/ are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate...
Cycas revoluta (Sotetsu [Japanese ソテツ], sago palm, king sago, sago cycad, Japanese sago palm) is a species of gymnosperm in the family Cycadaceae, native...
especially the sago cycad, Cycas revoluta. The sago cycad is also commonly known as the sago palm, although this is a misnomer as cycads are not palms. Extracting...
Cycas is a genus of cycad, and the only genus in the family Cycadaceae with all other genera of cycad being divided between the Stangeriaceae and Zamiaceae...
Zamia furfuracea is a cycad endemic to southeastern Veracruz state in eastern Mexico. Although not a palm tree (Arecaceae), its growth habit is superficially...
Lebombo cycad is the common name for two closely related species of cycads native to the Lebombo Mountains: Encephalartos lebomboensis Encephalartos senticosus...
Encephalartos woodii, Wood's cycad, is a rare cycad in the genus Encephalartos, and is endemic to the oNgoye Forest of KwaZulu-Natal, South Africa. It...
be "true palms" in the family Arecaceae, or cycads with a palm-like appearance. Sago produced from cycads must be detoxified before consumption. Plants...
5 species of cycad listed as Extinct in the Wild: Encephalartos brevifoliolatus, Escarpment cycad Encephalartos heenanii, Heenan's Cycad Encephalartos...
is a palm-like cycad in the family Zamiaceae, with a localized distribution in Limpopo, South Africa. Its common names, Modjadji's cycad or Modjadji's...
Encephalartos lehmannii is a low-growing palm-like cycad in the family Zamiaceae. It is commonly known as the Karoo cycad and is endemic to South Africa. The species...
brevifoliolatus, the escarpment cycad, is a cycad in the African genus Encephalartos. It is extinct in the wild. The escarpment cycad was found in short grasslands...
palm-like cycad in the family Zamiaceae. It is endemic to South Africa and is commonly known as Thunberg's cycad, breadpalm or broodboom. This cycad is listed...
Encephalartos caffer, the Eastern Cape dwarf cycad, is a rare cycad from the genus Encephalartos. It typically has an underground stem, with a small portion...
Encephalartos ferox, a member of the family Zamiaceae, is a small cycad with 35 cm wide subterranean trunk. It gets its name from the Latin word ferocious...
Luthrodes pandava also called the Plains Cupid or cycad blue, is a species of lycaenid butterfly found in South Asia, Myanmar, United Arab Emirates, Indochina...
(Purpus' cycad). Other common names include the cycad scale, the sago palm scale, and the Asian cycad scale. This is a serious pest of cycads which can...
The Cycad Nature Reserve is a small reserve near Bathurst for the purpose of conserving the critically endangered cycad Encephalartos latifrons. Near...
Encephalartos altensteinii is a palm-like cycad in the family Zamiaceae. It is endemic to South Africa. The species name altensteinii commemorates Altenstein...
Kamrup, Assam in northeast India. The species is one of the most widespread cycads. It is found in the northeastern part of India (Assam, Manipur, Meghalaya...
Dioon is a genus of cycads in the family Zamiaceae. It is native to Mexico and Central America. Their habitats include tropical forests, pine-oak forest...
The Palm and Cycad Arboretum at the Florida State College at Jacksonville is located on the south campus at 11901 Beach Boulevard, Jacksonville, Florida...
'revealed seeds') are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes, forming the clade Gymnospermae. The term gymnosperm...
Cycasin is a carcinogenic and neurotoxic glucoside found in cycads such as Cycas revoluta and Zamia pumila. Symptoms of poisoning include vomiting, diarrhea...
Fossil Cycad National Monument was a national monument in the U.S. state of South Dakota beginning in 1922. The site contained hundreds of fossils of...
Encephalartos latifrons (known as the Albany Cycad) is a species of cycad that is native to Eastern Cape province in South Africa at elevations of 200...
Lepidozamia hopei, commonly known as Hope's cycad or Zamia palm, is a species of cycad in the family Zamiaceae, endemic to the Australian state of Queensland...
bin Muhammed Al Thani. The preservation accommodates the World Heritage Cycad Gene Bank (WHCGB), which operates in conjunction under formal agreement...
Global Information
