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Gene flow  Biology  - Genetics ]

Dictionary of botanic terminology - index of names

Synonyms: Gene migration
     
  The movement and exchange of genes from one species or population to another.  
     
A mechanism for evolutionary change resulting from the exchange of genetic traits between populations by movement of individuals, gametes, or spores. It involves the spread of new variants among different populations through dispersal. Lack or low gene flow is considered detrimental because it does not yield a great amount of variability (gene pool) from which the population can use to overcome changing environmental conditions.
     

 


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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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