Caia is a genus of small fossil plants of Late Silurian age (around 430 to 420 million years ago). The diagnostic characters are naked parallel-sided axes branching isotomously, terminating in vertically elongate sporangia (spore-forming organs) which bear spinous emergences particularly at the distal ends. Spores are trilete and retusoid.[1] The only known species is from Hereford, England.
| Caia Temporal range:
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|---|---|
Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Streptophyta |
| Clade: | Embryophytes |
| Clade: | Polysporangiophytes |
| Class: | †Horneophytopsida (?) |
| Genus: | †Caia Fanning et al. (1990)[1] |
| Species | |
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†C. langii Fanning et al. (1990)[1] | |
Cladistic analysis suggests that the genus may belong to the Horneophytopsida, a class of the polysporangiophytes, as it lacks vascular tissue and has branched stems bearing sporangia.[2] For the cladogram, see the Horneophytopsida article.
References
edit- ^ a b c Fanning, U.; Edwards, D. & Richardson, J.B. (1990), "Further evidence for diversity in late Silurian land vegetation", Journal of the Geological Society, 147 (4): 725–728, Bibcode:1990JGSoc.147..725F, doi:10.1144/gsjgs.147.4.0725, S2CID 131527489725-728&rft.date=1990&rft_id=https://api.semanticscholar.org/CorpusID:131527489#id-name=S2CID&rft_id=info:doi/10.1144/gsjgs.147.4.0725&rft_id=info:bibcode/1990JGSoc.147..725F&rft.aulast=Fanning&rft.aufirst=U.&rft.au=Edwards, D.&rft.au=Richardson, J.B.&rfr_id=info:sid/en.wikipedia.org:Caia (plant)" class="Z3988">
- ^ Kenrick, Paul & Crane, Peter R. (1997), The Origin and Early Diversification of Land Plants: A Cladistic Study, Washington, D.C.: Smithsonian Institution Press, ISBN 978-1-56098-730-7
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