Uskiella

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]

Uskiella
Temporal range: Early Devonian
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Stem group: †Rhyniophytes (?)
Genus: †Uskiella
Shute & D.Edwards 1989[1]
Species

†U. spargens Shute & D.Edwards 1989
†U. reticulata Fanning et al. 1992

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
  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
  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, retrieved 2011-01-27
  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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