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Pappus   [ Botany  ]

Dictionary of botanic terminology - index of names

 
     
  A modified calyx crowning the ovary (achene) composed by a cluster of bristles, scales, featherlike hairs or a mixture of these in plants of the Family Compositae; may aid in seed dispersal.  
     
A pappus is a highly modified calyx, which is a funnel of sepals. Each tiny floret on the head of a plant in the Asteraceae has one, and in some cases these are modified into more or less elaborate bristles that act as a parachute. And by the way, each seed is actually a separate fruit called an achene and pappus greatly helps wind dispersing such seed.
 
     


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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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