Osmundaceae
Royal fern ( Osmunda regalis )
The Königsfarngewächse, also called Rispenfarngewächse, ( Osmundaceae ) are a family of class rights the ferns. It is divided into three genera with about 20 species. There are terrestrial ferns growing. Based on their characteristics, the family is placed in its own order Osmundales.
Features
Most members had a short tree-like stem, but usually hidden in today's representatives on the ground. The trunk is a leaf-trace - or sheet - root-stem; that is, the largest part of the stem is formed by leaf feet and roots.
The trunk is a siphonostele with inner xylem in the recent species. The leaves have stipules. The sporangia are sitting at own sporophylls ( Osmunda cinnamomea ) or on certain sections of the Trophophylle ( Osmunda regalis ). You are terminally on the terminal branches of the leaf on small stalks. In Todea and several fossil forms can be found on the underside of leaves pinned sporangia.
The sporangia are not grouped into sori and lack an annulus. They are large and contain 128 to 512 spores. The sporangium is multilayered. At the apex of the sporangium a group thickened cells, which causes the tearing of sitting (sometimes referred to as the annulus ). Indusium and chaff scales missing.
The prothallus is large, durable up to 4 inches and can be several years old. It is green and autotrophic lives above ground. Mycorrhiza has not been established.
The basic chromosome number is x = 22
Occurrence
The species are distributed from the temperate to the tropical zone.
System
The Osmundales are the sister group of all other leptosporangiaten ferns. The family is monophyletic and is divided into three genera with about 20 species:
- Leptopteris C. Presl: They often form up to 1 meter high strains, so it is " tree ferns ". There are seven species whose native Australia, New Zealand, the Pacific islands of Samoa and New Caledonia are Neuguineaund. Among them: Leptopteris hymenophylloides (A. Rich. ) C. Presl, Origin: New Zealand
- Leptopteris superba ( Colenso ) C. Presl, Origin: New Zealand
- Todea barbara (L.) T. Moore, Origin: South Africa, Australia and New Zealand
Getting the Osmundales between Marattiales and the other leptosporangiaten ferns. As they are to a time since the Permian known and had their main deployment in the Mesozoic; on the other morphologically, such as the thick-walled, solitary sporangia, their growing point and the prothallus. This position was underlined by molecular biology -based phylogenetic studies.
The name recalls the Norse thunder god Thor, who has the nickname " Osmunder ".
Pictures
Royal fern (O. regalis ), fully developed plant