Osmunda spectabilis

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Osmunda spectabilis
American royal fern
Osmunda spectabilis Kentucky.jpg
Scientific classification edit
Kingdom: Plantae
Class: Polypodiopsida
Order: Osmundales
Family: Osmundaceae
Genus: Osmunda
O. spectabilis
Binomial name
Osmunda spectabilis

Osmunda spectabilis or (American) royal fern is a species of fern doubtfully different from Osmunda regalis. Recent genetic studies have raised it from variety/subspecies to separate species.[citation needed]


Closeup of sterile frond

Osmunda spectabilis is an easy fern to recognize in the New World flora. Although it closely resembles species O. regalis, O. japonica, and O. lancea, only O. spectabilis is found growing naturally in the New World. The fronds of O. spectabilis can exceed 1 meter in length and are bipinnate. The pinnules are attached by a very narrow base. The plant produces separate sterile and fertile fronds. Fertile fronds are similar to the sterile fronds, in the lower and middle portions, but the top-most pinnae are fertile and they are much reduced and brown when mature in the early summer.[1]


Osmunda spectabilis was formerly considered to be a variety of Osmunda regalis (Osmunda regalis var. spectabilis). Another variety, Osmunda spectabilis var. brasiliensis, (formerly Osmunda regalis var. brasiliensis) also exists in tropical regions of Central and South America, but it is only recognized by some authors.

subg. Claytosmunda

Osmunda claytoniana

subg. Plenasium

Osmunda javanica

Osmunda banksiifolia

Osmunda vachellii

subg. Osmunda

Osmunda regalis

Osmunda spectabilis

Osmunda japonica

Osmunda lancea

Osmunda angustifolia, Osmunda bromeliifolia, and all extinct Osmunda species are missing from this cladogram. The classification is based on the genetic analysis presented in "The Paraphyly of Osmunda is Confirmed by Phylogenetic Analyses of Seven Plastid Loci."[2]

Distribution and Habitat[edit]

American royal fern is most commonly found growing in wetter soils such as those found in wet forests, bogs, and along streams and lakes.[3]


  1. ^ Fewless, Gary. "Royal Fern". Cofrin Center for Biodiversity, University of Wisconsin, Green Bay. Retrieved 11 September 2011.
  2. ^ 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 https://sites.duke.edu/pryerlab/files/2017/12/metzgar-et-al-osmunda-2008.original.pdf
  3. ^ "Royal Fern". Connecticut Botanical Society. Retrieved 11 September 2011.