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pH  [ Chemistry ]

Dictionary of botanic terminology - index of names

     
  pH is a measure of how acidic a substance is.  
     
Acidity is caused by hydrogen ions in a liquid, with more hydrogen ions making the liquid more acidic. However, the concentration of hydrogen ions can range from just a few ions per litre to many billions of ions per litre of liquid, so the pH scale has been designed to make the numbers a bit more manageable. pH numbers range from 1 to 14, with 1 being very acidic, and 14 being very  alkaline (the opposite of acidic) with neutral solutions (such as distilled water) having a pH of 7.
     

 


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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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