Cycads 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 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.
Cycas is a genus of cycad, and the only genus in the family Cycadaceae. About 113 species are accepted, which are native to the Indo-Pacific, East Africa and Madagascar. Cycas circinalis, a species endemic to India, was the first cycad species to be described in western literature, and is the type species of the genus. The best-known Cycas species is Cycas revoluta.
Cycas revoluta is a species of gymnosperm in the family Cycadaceae, native to southern Japan including the Ryukyu Islands. It is one of several species used for the production of sago, as well as an ornamental plant. The sago cycad can be distinguished by a thick coat of fibers on its trunk. The sago cycad is sometimes mistakenly thought to be a palm, although the only similarity between the two is that they look similar and both produce seeds.
Cycas angulata is a species of cycad in the genus Cycas, native to Australia in northeast Northern Territory and northwest Queensland.
Cycas armstrongii is a species of cycad in the genus Cycas, endemic to Northern Territory of Australia. It is found from the Finniss River in the west to the Arnhem Highway in the east, north of Pine Creek. It also occurs on the Tiwi Islands and the Cobourg Peninsula
Cycas arnhemica is a species of cycad in the genus Cycas, native to Australia, in the northwest of Northern Territory in Arnhem Land, after which it is named.
Cycas beddomei is a species of cycad in the genus Cycas, native to India, where it is confined to a small area of Andhra Pradesh state in the Tirumala Hills in scrubland and brush covered hills.
Cycas bifida is a species of cycad plant in the genus Cycas, native to southern China, and northern Vietnam.
Cycas bougainvilleana is a species of cycad in the genus Cycas, native to the islands northeast of Papua New Guinea, on New Britain, the Bismarck Archipelago and the Solomon Islands, where it occurs on or near the coast in calcareous coral sand dunes and in adjacent forests.
Cycas brachycantha is a species of cycad in the genus Cycas, native to northern Vietnam where it is endemic to Bắc Kạn Province. It grows in often soil-free cracks and crevices of limestone crests and ridges under the canopy of evergreen forests. It is found in Ba Bể National Park.
Cycas brunnea is a species of cycad in the genus Cycas, native to northern Australia in northwest Queensland and northeast Northern Territory in a small area straddling the border of the two regions. It occurs on exposed sites in savanna and creek valleys on sandstone and limestone derived soils, with moderate seasonal rainfall.
Cycas cairnsiana is a species of cycad in the genus Cycas, native to northern Australia in northern Queensland on the Newcastle Range.
Cycas chamaoensis is named after the only known habitat of this species, on and near Khao Chamao mountain in Khao Chamao District, Thailand. Stems are arborescent, either erect or decumbent. Leaves numerous, exceeding 60 per crown, 1.2-2.5 meters in length, ending in terminal spine. Petiole 30–60 cm, glabrous and partially spiny. Leaflets in 85-155 pairs, and lanceolate, glabrous and angled forward at 60-70 degrees.
Cycas circinalis, also known as the queen sago, is a species of cycad known in the wild only from southern India. Cycas circinalis is the only gymnosperm species found among native Sri Lankan flora.
Cycas micronesica is a species of cycad found on the island of Yap in Micronesia, the Marianas islands of Guam and Rota, and The Republic of Palau. It is commonly known as federico nut or fadang in Chamorro. The species, previously lumped with Cycas rumphii and Cycas circinalis, was described in 1994 by Ken Hill. Paleoecological studies have determined that C. micronesica has been present on the island of Guam for about 9,000 years. It is linked with Lytico-Bodig disease, a condition similar to amyotrophic lateral sclerosis (ALS), due to the neurotoxin BMAA found in its seeds, which were a traditional food source on Guam until the 1960s. The neurotoxin is present due to its symbiosis with cyanobacteria.
Cycas thouarsii, the Madagascar cycad, is an evergreen arborescent cycad in the genus Cycas. It is named after a French botanist Louis-Marie Aubert du Petit-Thouars (1758—1831).
Cycas panzhihuaensis is a rare and vulnerable species of cycad known in the wild only from Sichuan and Yunnan provinces in China. It can be seen at the South China Botanical Garden in Guangzhou and is also cultivated for horticulture, where it is often known as the Dukou sago palm.
Cycas zeylanica, common name maha-madu is a plant apparently at present endemic to the Andaman and Nicobar Islands. It was formerly also present in Sri Lanka, but the last remnants of the populations there were destroyed by the tsunami of December 2004.
Cycas orixensis is an endemic species found in the Indian state of Odisha. The species was recently discovered by Indian scientists, Rita Singh, P. Radha and J.S. Khuraijam
Cycas inermis is a vascular plant belonging to the family Cycadaceae, endemic to central and southern Vietnam. Its name in Vietnamese is Thiên tuế or Tuế lá quyết.
