Dioon

Cladus: Eukaryota
Regnum: Plantae
Divisio: Cycadophyta
Classis: Cycadopsida
Ordo: Cycadales
Subordo: Zamiineae
Familia: Zamiaceae
Subfamilia: Encephalartoideae
Tribus: Diooeae
Genus: Dioon
Species: D. califanoi - D. caputoi - D. edule - D. holmgrenii - D. mejiae - D. merolae - D. purpusii - D. rzedowskii - D. sonorense - D. spinulosum - D. tomasellii

Name

Dioon Lindl.
Type species: Dioon edule Lindl.

Synonym

* Platyzamia Zucc. Abh. Akad. Muench. iv. (1845) 23. t. 4

References

* Edward’s Bot. Reg. 29: misc. 59-60 (1843)
* Stevenson, D.W. Genus Dioon http://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/diokey.html

Dioon is a plant genus of 11 accepted species. They are cycads in the family Zamiaceae, and native to Mexico, Honduras, and Nicaragua. Their habitats include tropical forests, pine-oak forest, and dry hillsides, canyons and coastal dunes. In North America, the Dioon can be seen growing from southern Florida up to Savannah,Georgia.

Dioons are dioecious, palmlike shrubs with cylindrical stems, usually with many leaves. Leaf bases are persistent or shedding to leave smooth bark. The genus is commonly divided into two groups of distinct morphology. The first includes D. mejiae, D. rzedowskii, and D. spinulosum, "characterized generally by large fronds, well-developed trunks, and massive cones". The second group contains D. califanoi, D. caputoi, D. edule, D. holmgrenii, D. merolae, D. purpusii, D. sonorense, and D. tomasellii, which are "less robust, with generally shorter trunks, considerably shorter fronds, and smaller cones".[3]

The leaves are pinnate, spirally arranged, interspersed with cataphylls, with leaflets not articulated and lacking a midrib. The lower leaflets are often reduced to spines. The sporophylls are not in vertical rows in cones, and the megasporophyll apices are broadly flattened, upturned, and overlapping.

Accepted species

Dioon califanoi De Luca & Sabato
Dioon caputoi De Luca et al.
Dioon edule Lindl.
Dioon holmgrenii De Luca et al.
Dioon mejiae Standl. & L.O.Williams
Dioon merolae De Luca et al.
Dioon purpusii Rose
Dioon rzedowskii De Luca et al.
Dioon sonorense (De Luca et al.) Chemnick et al.
Dioon spinulosum Dyer
Dioon tomasellii De Luca et al.

List source : [4]

References

1. ^ a b In: Edwards's Botanical Register 29: misc. 59-60. 1843. "Name - Dioon Lindl.". Tropicos. Saint Louis, Missouri: Missouri Botanical Garden. http://www.tropicos.org/Name/40031830. Retrieved February 15, 2010. "Annotation: as 'Dion' ; orth. & nom. cons.
Type Specimen: Dioon edule Lindl."
2. ^ Original Publication GRIN (October 5, 2007). "Dioon information from NPGS/GRIN". Taxonomy for Plants. National Germplasm Resources Laboratory, Beltsville, Maryland: USDA, ARS, National Genetic Resources Program. http://www.ars-grin.gov/cgi-bin/npgs/html/genus.pl?3756. Retrieved February 15, 2010. "Comments: this spelling conserved (nom. cons.)(Vienna ICBN Art. 14.11 & App. III) against the original spelling 'Dion' "
3. ^ Norstog, K.J. & Nichols, T.J. (1997). The biology of the cycads. Cornell University Press.
4. ^ GRIN. "Complete List of Accepted Species Records for genus Dioon". Taxonomy for Plants. National Germplasm Resources Laboratory, Beltsville, Maryland: USDA, ARS, National Genetic Resources Program. http://www.ars-grin.gov/cgi-bin/npgs/html/splist.pl?3756. Retrieved February 15, 2010.