Pill ferns
| Pill ferns | ||||||||||||
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Ordinary pill fern , illustration from Thomé: Flora of Germany, Austria and Switzerland |
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| Pilularia | ||||||||||||
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The pill ferns ( Pilularia ) are a genus of ferns from the family of the clover family , in which the leaves are rush-like thread-like. They are also sometimes placed in a family of their own, Pilulariaceae.
Description and location requirements
The plants live aquatically in shallow water, sometimes also on open muddy ground, but at least in temporarily flooded areas. Like all clover plants, they form a long rhizome that creeps on the ground and branches dichotomously . Roots arise at the nodes of this main axis.
The leaf fronds protruding upwards from the rhizome do not have a leaf blade, but are more or less thread-like or rush-shaped. As a result, the plants have a grass-like habit , but can be distinguished from grasses by the curled up young leaf fronds.
The dark brown sporocarpies sit next to the tip of short, subterranean and unbranched side branches that arise at the base of the leaves. It is also typical of the genus that the sporocarpia contain only two to four sori , which in turn contain microsporangia and macrosporangia . When the fruit ripens, the sporocarp opens with two to four valves, depending on the number of sori, and releases its contents embedded in a gelatinous drop, in which the gametophytes also grow and fertilization takes place.
The German and scientific names of the genus are derived from the shape of the sporocarp, which is reminiscent of pills.
Types and distribution
The genus consists of six species with a strongly disjoint area:
- American pill fern ( Pilularia americana A. Braun ), a species that is closely related to the European common pill fern, and whose range consists of three disjoint areas in the west, middle and east of North America .
- Common pill fern ( Pilularia globulifera L. ), from the Atlantic western and central Europe
- Small pill fern ( Pilularia minuta Durieu ex A. Braun ), from the Mediterranean region from Morocco and Portugal to Cyprus and Turkey. It differs from the common pill fern by the leaves, which are no more than 4 cm long, the sporocarpia with only 2 chambers and a diameter of <1 mm.
- Bolivian pill fern ( Pilularia mandonii A. Braun ); it grows at an altitude of approx. 5000 m in the Bolivian Andes .
- Australian pill fern ( Pilularia novae-hollandiae A. Braun ), a species from Australia and Tasmania .
- New Zealand pill fern ( Pilularia novae-zealandiae Kirk ), a New Zealand species.
Sources and further information
literature
- Urania plant kingdom. Volume 2: mosses, ferns, naked plants 1st edition 1992, Urania-Verlag, Leipzig 1992, ISBN 3-332-00495-6 .
- Jaakko Jalas, Juha Suominen: Atlas Florae Europaeae. Volume 1, Helsinki 1972.
Web links
- Pill ferns. In: FloraWeb.de.
- Flora of North America - Pilularia