Pneumatophore
Pneumatophores ( Greek πνεῦμα , pneuma : "air flow"; φορός , phorós: "carrying") or respiratory roots are structures that are formed by the underground root system of some swamp or mangrove trees . They break through the soil surface through negative gravitropic growth ( contrary to gravity ).
Trees with pneumatophores grow in water-saturated, oxygen-poor soils. In these soils, the oxygen demand of the root tissue cannot be met by diffusion from the area around the roots alone ; the pneumatophores serve as roots of breath for the plants. About Lentizellen in their above-ground portion of air in under the gas-tight, corked bark lying interzellularenreiche Aerenchym diffuse. During measurements on mangroves it was found that the underground root system is able to generate a negative pressure through its oxygen consumption, which leads to a gas exchange through mass flow with the surface air; it is assumed that the carbon dioxide released by respiratory processes dissolves in the water surrounding the roots. In addition, diffusion processes must play a role in gas exchange.
If the above-ground section of the pneumatophores is completely flooded, the surface tension of the water prevents the penetration of liquid via the lenticels . In the submerged state, no gas exchange is possible and permanent flooding, e.g. B. by damming a tidal channel, can lead to the death of the root system.
Pneumatophores are u. a. formed by the mangrove trees Avicennia (subfamily Avicennioideae within the acanthus family ), Sonneratia ( loosestrife ) and (optional) by Laguncularia ( winged family ). Also cypress knee and stilt roots can not take breathing roots the function.
The upper swimming buoys of the state jellyfish are also called pneumatophores .
literature
- Tomlinson, PB (1986): The Botany of Mangroves. Cambridge University Press, Cambridge. 419 pp. ISBN 0-521-46675-X
