Aquatic plant

Aquatic plants or hydrophytes ( from Greek: ὕδωρ Hydor, "water" and φυτόν Phyton, "plant" ) are plants that live entirely or partially under water. There are land plants that have secondarily adapted to life in the water. Aquatic plants are found in freshwater, brackish and sea water.

Subdivision and Examples

Based on their growth form can be divided aquatic plants into the following groups:

• Free-floating aquatic plants ( Pleustophyten ) free-floating under water, more than the flowers will be spread over the surface. Examples are many water hoses ( Utricularia ).
• Swimming at the surface: the leaves are in exchange with the air. Examples are the water hyacinth, the floating ferns ( Salvinia ) and most species of duckweed ( Lemna ).

• Plants, partly assimilate partly submerged. Mostly swimming and floating-leaf plants such as arrowhead, lotus plants, floating pondweed, floating heart, Nymphaeaceae

• Plants that remain capable of assimilation under water: these are a few reed - plants that can penetrate far into the waters, as the Lakeshore Bulrush ( Schoenoplectus lacustris ) and the pond horsetail ( Equisetum fluviatile ).
• Plants assimilate only water and whose leaves die off under water: these are the most reed plants such as reeds (Phragmites ), such as reeds (Phragmites australis).

In principle, then, to distinguish between the immersion plants ( submerged plants, completely submerged ) and floating plants (at the surface ). The second pair are Radikante ( rooted ) and Errante ( free-floating and floating).

Adjustments

Because the shapes are very diverse within the group of aquatic plants, there are also a variety of adaptations that occur partly in many, sometimes only in some representatives.

• Many aquatic plants, especially those in stagnant water, have air tissue ( aerenchyma ), via the oxygen in the stems and roots can reach.
• Free floating plants are partially greatly reduced, as the floating ferns and fern Azolla. The most reduced flowering plants are duckweed plants: Wolffia ever makes no roots and no more vascular bundles, the leaves are reduced to knopfigen thalli.
• Submerged plants are dependent in their carbon supply for photosynthesis to the much lower levels in the water. Submerged plants in standing water bodies therefore have narrow or slashed leaves ( Elodea ). The cuticle is thin. Chloroplasts sitting in the epidermis, which normally is free of chloroplast in plants. Thus, the diffusion process of the carbon dioxide is reduced. The lack of perspiration they can take no mineral salts from the soil. My xylem is reduced. The roots serve only the anchorage. However, since the water has a low nutrient content, water hoses have become carnivorous plants.
• Some of submerged plants are also pollinated by water ( hydrophilic ). Others, however, bring their flowers to the surface and are pollinated by wind or animals.
• Plants in fast-flowing waters are also subject to addition to the factors already mentioned, the mechanical load. But the supply of carbon dioxide and nutrients through the movement of the water is better than in the standing water. They usually possess stem axis cable -type structure, with a centrally located, solid xylem. The leaves are usually finely divided. Examples are the types of group water crowfoot. However, you can also leaves out of the water form, but like ordinary leaves. So a plant produces two different leaf shapes ( Heterophyllie ). Another group in fast-flowing waters are the Podostemaceae in tropical rivers.
• Plants in the sea water, such as sea grasses, mangroves and salt marsh plants, also have to cope with the physiological effects of sea salt, compare salt plant.

Aquatic plants as food

Because of its energy resources, water plants are preferred food of moose, as they are protein -, mineral- and sodium- rich.

Documents

• Roland Ennos, Eliza Betz Sheffield: Plant Life. Blackwell Science, Oxford, inter alia, 2000, ISBN 0-86542-737-2, pp. 171-189.
• Wolfgang Engelhardt: What lives in ponds, stream and pond? Plants and animals in our waters. An introduction to the study of the life of inland waters. 14th revised and enlarged edition. Franckh-Kosmos, Stuttgart 1996, ISBN 3-440-06638- X, pp. 66-74.