Osmunda

Osmunda Temporal range: Triassic–recent PreЄ Є O S D C P T J K Pg N
Osmunda regalis
Scientific classification
Kingdom:	Plantae
Division:	Pteridophyta
Class:	Polypodiopsida /  Pteridopsida (disputed)
Order:	Osmundales
Family:	Osmundaceae
Genus:	Osmunda L.
Species
Osmunda japonica Osmunda lancea Osmunda regalis Osmunda spectabilis Osmunda angustifolia Osmunda banksiifolia Osmunda bromeliifolia Osmunda javanica Osmunda vachellii Osmunda claytoniana †Osmunda claytoniites †Osmunda wehrii †Osmunda greenlandica †Osmunda vancouverensis

Osmunda is a genus of primarily temperate-zone ferns of family Osmundaceae. Five to ten species have been listed for this genus.

The species have completely dimorphic fronds or pinnae (hemidimorphic), green photosynthetic sterile fronds, and non-photosynthetic spore-bearing fertile pinnae, with large, naked sporangia. Because of the large mass of sporangia that ripen uniformly at the same time to a showy golden color, the ferns look as if they are in flower, and so this genus is sometimes called the "flowering ferns".

The genus is known in the fossil record back to the Triassic period from fragmentary foliage nearly identical to the living Osmunda claytoniana.

Paleontological evidence indicates that Osmunda claytoniana, a reputed “living fossil,” has maintained evolutionary stasis for at least 180 million years.

The following species actually belong in the separate genus Osmundastrum, even though they have long been regarded as part of Osmunda:

Osmunda species are used as food plants by the larvae of some Lepidoptera species including the engrailed.

One of the species, the cinnamon fern (Osmundastrum cinnamomeum) forms huge clonal colonies in swamp 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 osmundine and used horticulturally, especially in propagating and growing orchids.

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Wikipedia