Caia (plant)

Caia Temporal range: Late Silurian PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Plantae
Clade:	Streptophyta
Clade:	Embryophytes
Clade:	Polysporangiophytes
Class:	†Horneophytopsida (?)
Genus:	†Caia Fanning et al. (1990)[1]
Species
†C. langii Fanning et al. (1990)[1]

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.

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

1. 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 131527489
2. 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