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Common Stains and Mounting Media for Botany Specimens

Botany specimens from differing divisions (based on their taxonomy) respond to stains in a unique way. Stains that Bryophytes require might not be the same for Algae or Fungi, or even Pteridophytes.

The most commons stains used in laboratory work are Aniline blue, Fast green, Safranin, Cotton blue, Methylene blue or Crystal violet. Media used for mounting may vary between Glycerine 10%, Glycerine jelly, Lactophenol, Erythrosine or Canada Balsam (or D.P.X. Mountant) depending on whether they are for temporary or permanent preparations.

Algae: Temporary preparations

  • Single staining: Aniline blue – 0.1% aqueous, Fast green – 0.5% aqueous, Safranin – 0.5% aqueous
  • Mounting media: Glycerine 10 % or glycerine jelly

Fungi: temporary preparations

  • Single staining: Cotton blue, Analine blue
  • Mounting media: Lactophenol or glycerine 10%

Bryophytes: Temporary preparations

  • Single staining: Safranin and Fast green
  • Mounting media: glycerine 10% or glycerine jelly

Pteridophytes: Temporary and permanent preparations

Double staining

  • Primary stains: Safranin and Crystal violet
  • Secondary stains: Fast green and Erythrosine
  • Mounting media: Glycerine 10% for temporary preparations and Canada Balsam or D.P.X.. Mountant for permanent preparations.

Gymnosperms: Temporary and permanent preparations

Double staining

  • Primary stains: Safranin and Crystal violet
  • Secondary stains: Fast green and Erythrosine
  • Mounting media: Glycerine 10% for temporary preparations and Canada Balsam or D.P.X.. Mountant for permanent preparations.

Mixtures of some common stains

Crystal violet:

  • Crystal violet: 3 gms
  • Distilled water: 80 ml
  • Ethyl alcohol (95%): 20 ml, dissolved and mixed with 0.8 gms of ammonium oxalate.

Methylene blue:

  • Methylene blue: 0.3 gms
  • (0.01%) distilled water – 100 ml
  • Ethyl alcohol (95%): 30 ml, dissolved and mixed with potassium hydroxide

Safranin:

  • Safranin: 0.25 gms
  • Alcohol (95%): 10 ml
  • Distilled water: 100 ml

Bacteria can be divided into gram negative and gram positive bacteria. Gram’s stain is used for this purpose and help with microscopic studies of the same.

Gram’s iodine solution: iodine – 1 gm, potassium iodide, 2 gms and distilled water 300 ml.

Steps to Gram’s staining

  • Stain specimen in crystal violet for one minute
  • Wash briefly in water Immerse in Gram’s iodine solution for a minute
  • Wash in water
  • Blot dry
  • Decolorize in 95% ethyl alcohol for 30 seconds; agitate
  • Wash in water
  • Counter-stain with safranin for 10 seconds
  • Wash dry
  • Mount with cover glass and examine

After you follow the above steps, you will see that some bacteria are colored violet from the violet stain, while others will appear red, indicating gram negative and gram positive bacteria.

Amanda Dcosta
 

Amanda writes about botany and plants from the deserts of Oman where summer temperatures climb to 130 Fahrenheit. Amanda has a BSc in Botany and is a co-author of Encyclopedia of Cultivated Plants: From Acacia to Zinnia. Read more articles by Amanda.

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