Uskiella

Uskiella; Temporal range: Early Devonian PreꞒ Ꞓ O S D C P T J K Pg N
	Uskiella spargens at fig f-h
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Stem group:	†Rhyniophytes (?)
Genus:	†Uskiella; Shute & D.Edwards 1989
Species
	†U. spargens Shute & D.Edwards 1989; †U. reticulata Fanning et al. 1992

Uskiella is a genus of small fossil plants of Early Devonian age (around 420 to 390 million years ago). The diagnostic characters are naked axes branching isotomously, terminating in ellipsoidal, vertically elongate flat sporangia which split longitudinally into two valves.^[1] Spores of U. reticulata have a reticulate appearance.^[2] Coalified specimens have been reported from Wales,^[2] with a possible occurrence in Australia.^[1]

The relationships of the genus are not clear because many anatomical details remain unknown. In 2004, Crane et al. published a cladogram for the polysporangiophytes in which Uskiella is basal to the lycophytes (clubmosses and relatives).^[3]

tracheophytes

† Rhyniaceae (Huvenia, Rhynia, Stockmansella)

† basal groups (Aberlemnia caledonica [=Cooksonia caledonica], Cooksonia pertoni)

† basal groups	Cooksonia cambrensis, Renalia, Sartilmania, Uskiella, Yunia

	lycophytes

euphyllophytes

Hao and Xue in 2013 listed the genus as a rhyniophyte.^[4]

References

^ ^a ^b ^c Shute, C.H. & Edwards, D. (1989), "A new rhyniopsid with novel sporangium organization from the Lower Devonian of Wales", Botanical Journal of the Linnean Society, 100 (2): 111–137, doi:10.1111/j.1095-8339.1989.tb01713.x
^ ^a ^b Fanning, U.; Edwards, D. & Richardson, J.B. (1992), "A diverse assemblage of early land plants from the Lower Devonian of the Welsh Borderland", Botanical Journal of the Linnean Society, 109 (2): 161–188, doi:10.1111/j.1095-8339.1992.tb00264.x
^ Crane, P.R.; Herendeen, P. & Friis, E.M. (2004), "Fossils and plant phylogeny", American Journal of Botany, 91 (10): 1683–99, doi:10.3732/ajb.91.10.1683, PMID 21652317
^ Hao, Shougang & Xue, Jinzhuang (2013), The early Devonian Posongchong flora of Yunnan: a contribution to an understanding of the evolution and early diversification of vascular plants, Beijing: Science Press, p. 329, ISBN 978-7-03-036616-0, retrieved 2019-10-25

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[ShuteEdwards1989-1] Shute, C.H. & Edwards, D. (1989), "A new rhyniopsid with novel sporangium organization from the Lower Devonian of Wales", Botanical Journal of the Linnean Society, 100 (2): 111–137, doi:10.1111/j.1095-8339.1989.tb01713.x

[Fanningetal1992-2] Fanning, U.; Edwards, D. & Richardson, J.B. (1992), "A diverse assemblage of early land plants from the Lower Devonian of the Welsh Borderland", Botanical Journal of the Linnean Society, 109 (2): 161–188, doi:10.1111/j.1095-8339.1992.tb00264.x

[3] Crane, P.R.; Herendeen, P. & Friis, E.M. (2004), "Fossils and plant phylogeny", American Journal of Botany, 91 (10): 1683–99, doi:10.3732/ajb.91.10.1683, PMID 21652317

[HaoXue13-4] Hao, Shougang & Xue, Jinzhuang (2013), The early Devonian Posongchong flora of Yunnan: a contribution to an understanding of the evolution and early diversification of vascular plants, Beijing: Science Press, p. 329, ISBN 978-7-03-036616-0, retrieved 2019-10-25

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