Osmundastrum

Osmundastrum is genus of leptosporangiate ferns in the family Osmundaceae with one living species, Osmundastrum cinnamomeum, the cinnamon fern. It is native to the Americas and eastern Asia, growing in swamps, bogs and moist woodlands.

Osmundastrum
Temporal range:
Developing spore-bearing frond and several sterile fronds in late spring

Secure  (NatureServe)[1]
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Division: Polypodiophyta
Class: Polypodiopsida
Order: Osmundales
Family: Osmundaceae
Genus: Osmundastrum
(C.Presl) C.Presl
Type species
Osmundastrum cinnamomeum
(von Linné 1753) Presl 1848
Species
  • O. cinnamomeum
  • †O. dubiosum (Hollick) Chelebaeva
  • †O. gvozdevae[2]
  • †O. indentatum[3]
  • †O. precinnamomeum(?)[3]
  • †O. pulchellum[4]
Synonyms
  • Osmunda (Osmundastrum) Presl 1845

In North America it occurs from southern Labrador west to Ontario, and south through the eastern United States to eastern Mexico and the West Indies; in South America it occurs west to Peru and south to Paraguay. In Asia it occurs from southeastern Siberia south through Japan, Korea, China and Taiwan to Myanmar, Thailand and Vietnam. Osmundastrum cinnamomeum has a fossil record extending into the Late Cretaceous of North America, approximately 70 million years ago, making it one of the oldest living plant species.[5][6] The fossil records of the genus extend into the Triassic.

Characteristics
Close-up of the pinnae of a sterile frond
Sterile fronds in late summer

Osmundastrum cinnamomeum is a deciduous herbaceous plant that produces separate fertile and sterile fronds. The sterile fronds are spreading, 30–150 cm (0.98–4.92 ft) tall and 15–20 cm (5.9–7.9 in) broad, pinnate, with pinnae 5–10 cm (2.0–3.9 in) long and 2–2.5 cm (0.79–0.98 in) broad, deeply lobed (so the fronds are nearly, but not quite, bipinnate). The fertile spore-bearing fronds are erect and shorter, 20–45 cm (7.9–17.7 in) tall; they become cinnamon-colored, which gives the species its name. The fertile leaves appear first; their green color slowly becomes brown as the season progresses and the spores are dropped. The spore-bearing stems persist after the sterile fronds are killed by frost, until the next season. The spores must develop within a few weeks or fail.

The Osmundastrum cinnamomeum fern forms huge clonal colonies in swampy areas. These ferns form massive rootstocks with densely matted, wiry roots. This root mass is an excellent substrate for many epiphytal plants. They are often harvested as osmunda fiber and used horticulturally, especially in propagating and growing orchids. Cinnamon Ferns do not actually produce cinnamon; they are named for the color of the fertile fronds.

Classification
Spore-bearing frond

Traditionally, this plant has been classified as Osmunda cinnamomea L. However, recent genetic and morphological evidence (Metzgar et al. 2008; Jud et al. 2008) clearly demonstrate that the cinnamon fern is a sister species to the entire rest of the living Osmundaceae. Cladistically, it is either necessary then to include all species of the Osmundaceae, including Todea and Leptopteris in the genus Osmunda, or else it is necessary to segregate the genus Osmundastrum. O. cinnamomeum is the sole living species in the genus,[7] although it is possible that some additional fossils should be assigned to Osmundastrum.[8]

Formerly, some authors included the interrupted fern, Osmunda claytoniana, in the genus or section Osmundastrum, because of its gross apparent morphological similarities. However, detailed morphology and genetic analysis have proven that the interrupted fern is actually a true Osmunda. This is borne out by the fact that it is known to hybridize with the American royal fern, Osmunda spectabilis to produce Osmunda × ruggii in a family in which hybrids are rare, while Osmundastrum cinnamomeum has no known hybrids.

Osmundastrum cinnamomeum is considered a living fossil because it has been identified in the geologic record as far back as 75 million years ago.[8] The oldest member of the genus is O. indentatum from the Triassic of Tasmania, Australia.[9]

The Asian and American populations of cinnamon fern are generally considered to be varieties of a single species, but some botanists classify them as separate species.[7] The Asian taxon is thus named Osmundastrum asiaticum.

Uses

According to the Native American Ethnobotany Database, cinnamon fern has been historically used by first nations tribes (Abnaki, Menominee) as a food source. The Iroquois and Cherokee tribes used the fern for a wide variety of medicinal purposes including as a cold remedy, gynecological aid, venereal aid, and as a remedy to snake bites.

A large cinnamon fern outcropping.

References
  1. "NatureServe Explorer 2.0 - Osmunda cinnamomea Cinnamon Fern". explorer.natureserve.org. Retrieved 9 October 2020.
  2. Bazhenova, N. V.; Bazhenov, A. V. (2019). "Stems of a New Osmundaceous Fern from the Middle Jurassic of Kursk Region, European Russia". Paleontological Journal. 53 (5): 540–550. doi:10.1134/S0031030119050034. S2CID 203848747. Retrieved 9 November 2021.
  3. Bomfleur, B.; Grimm, G. W.; McLoughlin, S. (2017). "The fossil Osmundales (royal ferns)—a phylogenetic network analysis, revised taxonomy, and evolutionary classification of anatomically preserved trunks and rhizomes". PeerJ. 5: e3433. doi:10.7717/peerj.3433. PMC 5508817. PMID 28713650. Retrieved 27 October 2021.
  4. Benjamin Bomfleur; Guido W. Grimm; Stephen McLoughlin (2017). "The fossil Osmundales (Royal Ferns)—a phylogenetic network analysis, revised taxonomy, and evolutionary classification of anatomically preserved trunks and rhizomes". PeerJ. 5: e3433. doi:10.7717/peerj.3433. PMC 5508817. PMID 28713650.
  5. Serbet, Rudolph; Rothwell, Gar W. (March 1999). "Osmunda cinnamomea (Osmundaceae) in the Upper Cretaceous of Western North America: Additional Evidence for Exceptional Species Longevity among Filicalean Ferns". International Journal of Plant Sciences. 160 (2): 425–433. doi:10.1086/314134. ISSN 1058-5893. S2CID 84290371.
  6. Rothwell, Gar W.; Stockey, Ruth A.; Smith, Selena Y. (December 2020). "Revisiting the Late Cretaceous Parataxodium wigginsii flora from the North Slope of Alaska, a high-latitude temperate forest". Cretaceous Research. 116: 104592. doi:10.1016/j.cretres.2020.104592. S2CID 224893472.
  7. Alan S. Weakley (April 2008). "Flora of the Carolinas, Virginia, and Georgia, and Surrounding Areas".
  8. Jud, Nathan, Gar W. Rothwell, and Ruth A. Stockey (2008). "Todea from the Lower Cretaceous of western North America: implications for the phylogeny, systematics, and evolution of modern Osmundaceae". American Journal of Botany. 95 (3): 330–339. doi:10.3732/ajb.95.3.330. PMID 21632358.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. Bomfleur, Benjamin; Grimm, Guido W.; McLoughlin, Stephen (2017-07-11). "The fossil Osmundales (Royal Ferns)—a phylogenetic network analysis, revised taxonomy, and evolutionary classification of anatomically preserved trunks and rhizomes". PeerJ. 5: e3433. doi:10.7717/peerj.3433. ISSN 2167-8359. PMC 5508817. PMID 28713650. S2CID 12235529.

Further reading
  • Metzgar, Jordan S., Judith E. Skog, Elizabeth A. Zimmer, and Kathleen M. Pryer (2008). "The Paraphyly of Osmunda is Confirmed by Phylogenetic Analyses of Seven Plastid Loci." Systematic Botany, 33(1): pp. 31–36.
  • Serbet, Rudolf, and Gar W. Rothwell (1999). "Osmunda cinnamomea (Osmundaceae) in the Upper Cretaceous of western North America: Additional evidence for exceptional species longevity among filicalean ferns." International Journal of Plant Sciences, 160: 425–433.
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