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Corona (in: Asclepiadaceae flower)    [ Botany ]
Synonym: Crown

Dictionary of botanic terminology
index of names

     
  The typical whorl of structures between the corolla and stamens in Asclepiadaceae family.  
     


The colourful corona of Stapelia flavopurpurea.
Outer corona   (Yellow with purple tip) and
Inner corona  (Pink with horned appendages)

The corona (Crown) is a characteristic androecial derived structure found in Asclepiadaceae flowers of variable form, colour and dimension , which is incorporated in the gynostegium (a complex fusion-product of androecium and gynoecium).

The corona typically consists of inner and outer lobes.

  • Inner corona: Usually the inner corona parts are inclined against the staminal column (a structure formed by the fusion of the stamens).
  • Outer corona: Outer corona lobes lie flat in the base of corolla or they are budged away from the column. They can be larger than the inner one or so reduced that they can’t even be found.

The unique and complex structures of corona and gynostegium are extremely elaborated and very dissimilar in different  genera and species  (Eventually variously keeled, horned and/or shaped ) and they are the most important factor for Asclepiadaceae classification.

 

 

For other meaning  of the word "Corona" see: Crown

 

See also: Asclepiadaceae flower anatomy

   

 


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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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