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Pollinium (Plural: Pollinia) [ Botany ]

Dictionary of botanic terminology - index of names

     
  A pollinium is the specific, pollen-bearing structure of Asclepiadaceae and Orchidaceae which is extracted by pollinators from a flower and transported for pollination to another flower.  
     
It is a mass of pollen grains fused by means of their wavy texture or fine threads, It originate from a single anther. This mass sticks together and during pollination is transported as a single unit.

 


 

A  pair of pollinia,  the typical pollen-bearing structure of Asclepiadaceae family.

   
 
Pollinarium (Plural: pollinaria)

 

     
  A functional unit in Orchid pollination that consists of two or more pollinia, stalk or stipe, and viscidium.  
     

A special thank for the photo to:
Andrea B. (Italy)


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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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