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Clade  [ Taxonomy  ]

Dictionary of botanic terminology - index of names

 
A clade is a group of species related by descent with a common ancestor. Such a group is called a monophyletic group. The classification system based on clades is called cladistics.
In biological systematics, a clade is a monophyletic grouping of taxa where all members share a common ancestor (the founder) and all offspring of members of the group (that is, all descendants of the founder), e.g. the cactus all evolved from a single common ancestor and are a 'clade'. The members of a clade are closely related to each other and have one or more derived features shared by all the members (synapomorphies).

 


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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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