Stangeriaceae

Stangeriaceae is the smallest family of the cycads, including only two extant genera, Stangeria and Bowenia. The family has been recognized based on some shared characters such as the presence of fused vacularized stipules, the lack or irregular production of cataphylls, and a few other anatomical traits[1]. Molecular[2][3][4] evidence suggests that the two genera of the Stangeriaceae belong in different positions within the Zamiaceae.

Stangeriaceae
Stangeria eriopus in coastal lowland forest,
South Africa
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Division: Cycadophyta
Class: Cycadopsida
Order: Cycadales
Suborder: Zamiineae
Family: Stangeriaceae
Schimp. & Schenk
Genera

Though today the family occurs only in South Africa and Queensland, Australia, potentially related fossils are found in other places in the globe. Cladistic studies suggested that the fossil taxon Mesodescolea from the Lower Cretaceous of Argentina has affinities with the Stangeriaceae, being sister to Stangeria[5]. This highly lobed fossil leaf from has been reinterpreted as an early angiosperm[6]. Another fossil from the Lower Cretaceous of Argentina, Eobowenia incrassata, has been suggested as the oldest relative of Bowenia.[7] The Paleogene genus Eostangeria from North America and Europe[8] may also have affinities with the Stangeriaceae.

References
  1. Stevenson, Dennis WM. (1992-04-01). "A formal classification of the extant cycads". Brittonia. 44 (2): 220–223. doi:10.2307/2806837. ISSN 1938-436X.
  2. Salas-Leiva, Dayana E.; Meerow, Alan W.; Calonje, Michael; Griffith, M. Patrick; Francisco-Ortega, Javier; Nakamura, Kyoko; Stevenson, Dennis W.; Lewis, Carl E.; Namoff, Sandra (2013-11-01). "Phylogeny of the cycads based on multiple single-copy nuclear genes: congruence of concatenated parsimony, likelihood and species tree inference methods". Annals of Botany. 112 (7): 1263–1278. doi:10.1093/aob/mct192. ISSN 0305-7364. PMC 3806525. PMID 23997230.
  3. Rai, Hardeep S.; O’Brien, Heath E.; Reeves, Patrick A.; Olmstead, Richard G.; Graham, Sean W. (2003-11-01). "Inference of higher-order relationships in the cycads from a large chloroplast data set". Molecular Phylogenetics and Evolution. 29 (2): 350–359. doi:10.1016/S1055-7903(03)00131-3. ISSN 1055-7903.
  4. Chaw, Shu-Miaw; Walters, Terrence W.; Chang, Chien-Chang; Hu, Shu-Hsuan; Chen, Shin-Hsiao (2005-10-01). "A phylogeny of cycads (Cycadales) inferred from chloroplast matK gene, trnK intron, and nuclear rDNA ITS region". Molecular Phylogenetics and Evolution. 37 (1): 214–234. doi:10.1016/j.ympev.2005.01.006. ISSN 1055-7903.
  5. Hermsen, Elizabeth J.; Taylor, Thomas N.; Taylor, Edith L.; Stevenson, Dennis Wm (2006). "Cataphylls of the Middle Triassic cycad Antarcticycas schopfii and new insights into cycad evolution". American Journal of Botany. 93 (5): 724–738. doi:10.3732/ajb.93.5.724. ISSN 1537-2197.
  6. Coiro, Mario; Martínez, Leandro C. A.; Upchurch, Garland R.; Doyle, James A. "Evidence for an extinct lineage of angiosperms from the Early Cretaceous of Patagonia and implications for the early radiation of flowering plants". New Phytologist. n/a (n/a). doi:10.1111/nph.16657. ISSN 1469-8137.
  7. Coiro,M.; Pott,C. (2017). "Eobowenia gen. nov. from the Early Cretaceous of Patagonia: indication for an early divergence of Bowenia?". BMC Evolutionary Biology. 17 (1): 97. doi:10.1186/s12862-017-0943-x. PMC 5383990. PMID 28388891.
  8. Kvaček, Zlatko; Manchester, Steven R. (1999-05-01). "Eostangeria Barthel (Extinct Cycadales) from the Paleogene of Western North America and Europe". International Journal of Plant Sciences. 160 (3): 621–629. doi:10.1086/314152. ISSN 1058-5893.
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