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Scale (synonym: squama) [ Botany ]

Dictionary of botanic terminology - index of names

Adjective: Scale-like, Squamiform, Scaly

Gymnocalycium baldianum budsIn botany a scale or squama is a small, thin, usually dry, often appressed plant structure, such as any of the protective leaves that cover a bud or the bract that subtends a flower in a sedge or a thin flake, an exfoliation of dead epidermis shed from the surface of the epidermis.


Left:
 scale and scale-like tepals on the floral tube of a Gymnocalycium.
 

(1) Scale leaf or scale-like leaf     [ Botany]
A scale or Scale-like leaves is a small sharp-pointed leaf with a broad base. They usually overlap on the stem.
(2) Bud scale    [ Botany]
A bud scale is a kind of specialized leaf or bract that protects and surrounds a dormant plant bud before the bud expands.
 (3) Scale  or scale leaves (bulb)  [ Botany]
Scales or scale leaves are also the fleshy leaves of a bulb.
The body of the bulb is made up of concentric layers of fleshy scales which are modified leaves. The scales are food and water storage organ that overlap and cover the bud.
 
(4) Scale or peltate hair  [ Botany]
A scale or peltate hair is a common type of trichome a plate or shield-shaped cluster of cells attached directly to the surface or borne on a stalk of some kind.



For example (on the left) a peltate  glandular  trichome
(5) Scale  ( Scale-like insect)  [  Phytoparasitology  ]
Scale is a diseased condition of plants caused by scale insects that attaches to plants and sucks plant fluids for nutrition. It coats itself with a covering (hence scale) that makes it quite resistant to pesticides, which are only effective against them when they are in the juvenile crawler stage. Scale, however can be controlled with horticultural oil, which suffocates them, or through biological controls.

 


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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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