Potamogeton praelongus
Leaved Pondweed ( Potamogeton praelongus )
The Langblättrige pondweed ( Potamogeton praelongus ) is a Wasserpflanzenart from the family of pondweed family ( Potamogetonaceae ).
Description
The Langblättrige pondweed is a perennial, herbaceous plant, reaching a length of up to 0.8 to 3 meters, is the stem in cross-section oval to round. The sessile leaves are under water and are arranged spirally. They are narrow ovate - lanceolate, at the base round and include the stem scheidig, the edge is smooth and entire, the tip rounded to obtuse. Floating leaves absent. The midrib stands out clearly, the side ribs are fine-meshed interconnected. The 3 to 8.1 inches long, filamentous stipules are linear - lanceolate, curled whitish to green, durable, and laterally.
Bloom time is from June to July, the inflorescence is a standing above the water surface, unbranched spike, it is cylindrical and 3.4 to 7.5 inches long. The Langblättrige pondweed is windbestäubend and the flowers are kronblattlos. To protect the reproductive organs, however, develop greenish appendages that resemble a four-leaf flower crown to the connectives of the anthers. The inflorescence axes are achselbürtig or terminal and reach a length of 9.5 to 53 centimeters.
The fruits are nutlets sessile (collective drupe ). They are green brown, obovate, achsabgewandt always and occasionally keeled laterally, from 4 to 5.7 mm long and 3.2 to 4 millimeters wide. The chromosome number is 2n = 52
Dissemination
The Langblättrige pondweed is widespread, it is found in Eurasia as well as North America ( Greenland to Mexico) from sea level to 3000 meters deep, pH - neutral to alkaline lakes and rivers.
In many European countries, their stocks have fallen sharply ( UK 25%, France 30%, Germany 60%, Czech Republic 90 %), reasons for the gradual disappearance of the species is mainly the increasing eutrophication of water bodies.
Evidence
- Erich Götz: Plants determine the computer. 2001, ISBN 382528168X
- Robert R. Haynes, C. Barre Hellquist: Potamogetonaceae. In: Flora of North America, Vol 22, ( Online), accessed on 17 November 2008