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(1) Sand   [ Geology - Agronomy ]
Adjective: Sandy

Dictionary of botanic terminology - index of names

     
  A loose soil constituent composed of grains of rock and minerals with diameters ranging between 0,05 mm and 2 mm.
Sand is larger than silt and smaller than gravel.
 

Sand is a naturally occurring granular and unconsolidated material of very diverse composition, found on beaches, in deserts, and in soil, resulting principally from rock disintegration composed by finely divided rock, especially quartz (that may include disintegrated shells and coral).
Sand ranges in diameter from 0,05 mm (very fine) to 2 mm (very coarse). An individual particle in this range size is termed a sand grain.
The next smaller size class is silt: particles below 0.05 mm down to 0.005 mm in size. The next larger size class above sand is gravel, with particles ranging up to 64 mm.

 

(2) Sand  [ Geography ]
     
  A tract of land covered with sand, as a beach or desert. Often used in the plural.
 
 
Sandy  (Adjective)
Synonym: Arenaceous
     
  Resembling or containing sand; or growing in sandy areas.
 
 
Sandy  soil [ Horticulture - Agronomy ]
Synonym: Light soil
     
  Course textured, granular soil, in consistency. Describes dry, light, friable, large-grained and free-draining soil, low in nutrients, derived from quartz or other rock.  
     
Because of the relative large size of sand particles (0.05-2.0 mm), sandy soils have trouble holding water and nutrients. They are commonly deficient in calcium and magnesium. Adding humus to sandy soils can help. When mixed with a heavier soil (one that is largely comprised of clay), sand can help provide aeration. Sand is also commonly mixed with seed for broadcasting and is a component in some potting-mix..  Most sand grains consist of quartz.
     
  As a soil textural class,  a sandy soil  has more than 85% of sand and not more than 10% clay.  
     

 


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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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