Christensenia (plant)

Christensenia
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Embryophytes
Clade: Tracheophytes
Division: Polypodiophyta
Class: Polypodiopsida
Order: Marattiales
Family: Marattiaceae
Genus: Christensenia
Maxon
Type species
Christensenia aesculifolia
(Blume) Maxon
Synonyms

Kaulfussia C.Presl

Christensenia is a genus of ferns in the botanical family Marattiaceae. The genus is confined to the Indo-Malayan region. The basal chromosome number for this genus is 2n=80.

Christensenia is unique in the Marattiaceae, because of its reticulate venation, palmately arranged leaves and radial synangia. Christensenia produces enormous amounts of spores, up to 7,000 spores per sporangium. The radial synangium is very similar to some of the fossil Asterothecaceae/Psaroniaceae, such as Scolecopteris. Christensenia itself has no fossil record. Christensenia is notable for having the largest known stomata of any land plant, and a stomatal structure that is permanently open, restricting the genus to high-humidity environments.[1][2]

Taxonomy

The Smith et al. classification of 2006, based on molecular phylogeny, placed Christensenia in Marattiaceae.[3] Subsequent classifications have maintained this placement.[4][5][6]

Species

Some taxonomists have recognized only one variable species of Christensia across its range, while others have described a small number of regionally restricted species including Christensenia assamica (Griff.) Ching from India and Christensenia cumingiana Christ from Mindanao.[7] The 1993 revision by Rolleri[1] recognized two species and one variety:

References

  1. 1 2 Rolleri, Cristina (1993). "Revision of the Genus Christensenia". American Fern Journal. 83 (1): 3–19. doi:10.2307/1547357. ISSN 0002-8444.
  2. ↑ Bell, Peter Robert; Hemsley, Alan R. (2000). Green plants: their origin and diversity (2nd ed.). Cambridge, UK ; New York: Cambridge University Press. ISBN 978-0-521-64109-8.
  3. ↑ Smith, Alan R.; Pryer, Kathleen M.; Schuettpelz, Eric; Korall, Petra; Schneider, Harald; Wolf, Paul G. (2006). "A classification for extant ferns" (PDF). Taxon. 55 (3): 705–731. doi:10.2307/25065646. JSTOR 25065646.
  4. ↑ Christenhusz, Maarten J. M.; Zhang, Xian-Chun; Schneider, Harald (2011). "A linear sequence of extant families and genera of lycophytes and ferns" (PDF). Phytotaxa. 19: 7–54. doi:10.11646/phytotaxa.19.1.2.
  5. ↑ Christenhusz, Maarten J.M.; Chase, Mark W. (2014). "Trends and concepts in fern classification". Annals of Botany. 113 (9): 571–594. doi:10.1093/aob/mct299. PMC 3936591. PMID 24532607.
  6. ↑ PPG I (2016). "A community-derived classification for extant lycophytes and ferns". Journal of Systematics and Evolution. 54 (6): 563–603. doi:10.1111/jse.12229. S2CID 39980610.
  7. ↑ Kubitzki, Klaus, ed. (1990), The families and genera of vascular plants. 1: Pteridophytes and gymnosperms, Berlin: Springer, ISBN 978-3-540-51794-8, retrieved 2026-06-22
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