Rion's water crowfoot

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Rion's water crowfoot
Ranunculus rionii, c, Tweeling.jpg

Rion's water crowfoot ( Ranunculus rionii )

Systematics
Eudicotyledons
Order : Buttercups (Ranunculales)
Family : Buttercup Family (Ranunculaceae)
Genre : Buttercup ( Ranunculus )
Subgenus : Water crowfoot (subgenus) ( Batrachium )
Type : Rion's water crowfoot
Scientific name
Ranunculus rionii
Lagger

Rion's water crowfoot ( Ranunculus rionii ), also called tender water crowfoot , is a species of the buttercup family (Ranunculaceae). This species belongs to the species group of the white-flowered water cockfoot ( Ranunculus aquatilis agg.) And is relatively unknown because it is often confused with the hairy water cockfoot.

description

Vegetative characteristics

Rion's water crowfoot is usually an annual, rarely perennial aquatic plant . The plant does not form floating leaves and reaches lengths of up to about one meter. It is rooted in water up to two meters deep. The bare, flooding stems with air chambers grow upright or lying down.

Adapted to life under water, the plant has finely divided, hair-shaped water leaves. Outside the water, these collapse like a brush. The egg-shaped stipules are more than 2/3 fused with the petiole. The lower water leaves are stalked up to 2 cm long, while the upper ones sit on the stem. The water leaves are polygonal in outline and threefold at the bottom. The leaf sections are not parallel, but strive stiffly apart, they are short-stalked and forked several times or in three parts. The thread-like leaf lobes spread limply on all sides. The leaves are usually longer than the distance between the stem nodes .

Flowers and fruits

The long flower stalks arise opposite the leaf base and are one to one and a half times as long as the leaf opposite. A few flowers emerge on the upper part of the stems and protrude above the surface of the water. The five-fold flower has a diameter of about one centimeter, which is small compared to other species of water crowfoot. The flower base is hairy. The five green, bare sepals are about 2.5 millimeters long. The five white petals yellow at the base do not overlap. Their shape is obovate with a rounded tip and they measure about 4 × 2 millimeters. The flower develops around 15 stamens , and nectar leaves are also formed. The nectar leaves are tubular, have pear-shaped mouths and are without cover scales.

The flowering period lasts from May to August.

The flower base is hairy and elongates at the fruiting time. From each flower a cylindrical head with 50 to 100 closely spaced, only 1 to 1.2 mm long and 0.6 to 0.8 mm wide, oval, always bald nuts is formed. These have four to ten transverse wrinkles and are spotted purple at the tip.

Chromosome number

The number of chromosomes is 2n = 16.

Similar species

This species is very similar to the hair-leaved water cockfoot ( Ranunculus trichophyllus ), but differs in that it has a bald head with 50 to 100 fruits. In the hair-leaved water crowfoot, the head of the fruit is spherical, the nuts are 1.4 to 1.9 mm long and 0.9 to 1.2 mm wide and always have bristly hair on the back towards the beak. Nevertheless, the species is little known and is therefore often confused. It also shows great variability in its leaf characteristics.

ecology

Sometimes the species completes its life cycle within a few weeks. The flowers are pollinated by insects or by self-pollination of the hermaphrodite flowers. It is spread by birds, usually together with other hydrophytes . Accordingly, many sites are located along the major bird migration routes. The seeds can apparently survive in the soil for a long time and remain viable.

Like all other Ranunculus species, Rion's water crowfoot is poisonous.

Occurrence

Rion's water buttercup is native to the temperate latitudes of Eurasia up to altitudes of around 700 meters. It was introduced in South Africa and western North America . In Europe it occurs scattered and often isolated in Switzerland , southwest Germany, France , the Czech Republic , Lower Austria , Slovenia and western Hungary . South of the Alps it only grows in northern Italy , and in south-eastern Europe it occurs in the area of ​​the Dalmatian and Adriatic coast from Slovenia to Greece and somewhat more frequently in Romania and the Crimea .

Rion's water crowfoot grows on moderately nutrient-rich, neutral to basic, clay-muddy (never gravelly) pond bottoms. It inhabits sunny, clear, ponds and ponds that warm up strongly in summer and partially or completely dry out. In Germany it is also found in quarry ponds, ditches and oxbow lakes in rivers with low currents. The weakly competitive plants can be found primarily in pioneer locations such as newly created pits in clay, sand or gravel soils. It occurs in companies of the Potamogetonion Association.

In Switzerland and in other European countries the species is on the red list of endangered plant species.

Systematics

This species belongs to the subgenus Batrachium (DC) A.Gray together with the other water crowfoot species . Ranunculus rionii was first described in 1848 by the Swiss botanist Franz Lagger . The epithet honors Canon Alphonse Rion (1809–1856), active as a natural scientist in the canton of Valais and first discoverer of this kind.

There are a number of synonyms for Rion's water crowfoot ( Ranunculus rionii Lagger ) . These are, with their respective references:

  • Ranunculus flaccidus var. Rionii (Lagger) Hegi - Ill. Fl. Mitt.-Eur., 3: 585 (1912) -
  • Ranunculus trichophyllus subsp. rionii (Lagger) Jáv. - Magyar Fl .: 370 (1924) -
  • Batrachium trichophyllum subsp. rionii (Lagger) CDKCook - Mitt.Bot . Munich, 3: 601 (1960)

swell

  • Christoph Käsermann: Ranunculus rionii Lagger - Rion's water cock foot - Ranunculaceae. In: Christoph Käsermann, Daniel M. Moser (Hrsg.): Information sheets on species protection - flowering plants and ferns. Federal Office for the Environment, Forests and Landscape, Bern 1999, pp. 242–243 (PDF file; 733 kB).

Individual evidence

  1. ^ A b Peter Wolff, Arno Schwarzer: Ranunculus rionii Lagger - a new aquatic plant in Germany. In: Floristic Newsletters. Volume 25, No. 2, 1991, pp. 69-85.
  2. ↑ a b CDK Cook: A monographic study of Ranunculus subgenus Batrachium (DC.) A. Gray. In: Communications from the Botanical State Collection, Munich. Volume 6, 1966, pp. 47-237.
  3. ↑ a b Erich Oberdorfer : Plant-sociological excursion flora for Germany and neighboring areas . With the collaboration of Angelika Schwabe and Theo Müller. 8th, heavily revised and expanded edition. Eugen Ulmer, Stuttgart (Hohenheim) 2001, ISBN 3-8001-3131-5 , pp.  418 .
  4. ↑ Franz Lagger: Ranuncuculus Rionii, a new Wasserranunkel Switzerland. In: Flora. Volume 31, No. 4, pp. 49-50 digitizedhttp: //vorlage_digitalisat.test/1%3Dhttp%3A%2F%2Fbiodiversitylibrary.org%2Fpage%2F42974~GB%3D~IA%3D~MDZ%3D%0A~SZ%3D~ double-sided%3D~LT%3D~ PUR% 3D .
  5. ↑ Jean-Claude Praz: Pouta Fontana, swamp in the Rhone plain (= booklet of the Natural History Museum. Volume 1). Musée cantonal d'histoire naturelle, Sion 1991, ISBN 2-88426-004-8 , passionate naturalist. Canon Alphonse Rion (1908-1856) , p. 20, limited preview in the Google book search.

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