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Biologycal Type

Dictionary of botanic terminology - index of names

A biological type is a  physical specimen(s) or the illustration of an organism selected by the author(s) of a species or by subsequent author(s)  to be the standard reference for the name which defines the characteristics of the whole species.

• Holotype, The single specimen described and considered  the standard reference of a new species name.
• Paratype, A biological specimen other than the holotype used for the development of the original description.
• Isotype, A duplicate specimen of the holotype collected in the same place and time.
• Allotype a comparative specimen of the opposite sex to the holotype
• Neotype a substitute specimen selected if the holotype was destroyed or otherwise lost
• Isoneotype  a duplicate of the neotype
• Syntypes. two or more specimens describing of a new species when the author did not select a holotype.
• Isosyntypes duplicates of a syntype.
• Lectotype One single specimen later selected from the syntypes as the definitive type example
• Paralectotypes After the definitive chosen of the lectotype the remainder syntypes become paralectotypes.
• Epitype A later specimen used as an interpretative type when the holotype, lectotype, or  neotype, is ambiguous.
• Topotypes,  The specimens collected at type locality,  from the topotypical population.

The various types described above are needed because many species description go back one or two centuries and type designation was not always done, types were not always well kept or preserved, or intervening events have resulted in destruction of original type material. Some older botanical types are actually illustrations rather than specimens.

 


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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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