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Arid  Ecology - Climatology  ]

Dictionary of botanic terminology - index of names

Noun: Aridity 
Lacking sufficient water or rainfall;
Lacking moisture, especially applied to regions where precipitation (rain or snow) is so deficient in quantity, or occurs at such times that they are insufficient to support vegetation. Extremely dry; the driest climates on our planet, often associated with the desert vegetation type. Semi-arid refers to places that are almost as arid as the deserts. Arid is considered the opposite of humid when speaking of climates.

Compared to wetter regions the arid regions (deserts) supports very little life however often give hospitality to a wealth of specialized living organism that usually remains hidden (especially during the daylight) or grow partially underground to preserve moisture.

See also: Dry; Desert; Drought, Xeric

 


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Holdfast roots  [ Botany  ]

Dictionary of botanic terminology - index of names

 
     
  Some species of climbing plants develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place.  
     
Climbing plants, like the poison ivy (Toxicodendron radicans), Boston ivy (Parthenocissus tricuspidata), and trumpet creeper (Campsis radicans),  develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place. Usually the Holdfast roots die at the end of the first season, but in some species they are perennial. In the tropics some of the large climbing plants have hold-fast roots by which they attach themselves, and long, cord-like roots that extend downward through the air and may lengthen and branch for several years until they strike the soil and become absorbent roots.

Major references and further lectures:
1) E. N. Transeau “General Botany” Discovery Publishing House, 1994
   

 

 

 

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