because they're are starches in the leucoplast
starches
To stain the starch in the leucoplasts so they are visible
It is crystal violet & stains all cells purple.
Leucoplasts are generally colourless. Iodine stains starches blue, so this is probably what you're seeing. Leucoplasts are a type of plastid, meaning they store and produce things in cells. Leucoplasts specifically tend to store starches which is why iodine turns them blue. Hope this helps!
aqueous iodine in the form of potassium iodide turns purple in the presence of starches in water.
iodine
The iodine stain can be removed from the paper by washing the stain in plenty of cold water. Paper distillation can also be used to remove the iodine stain from the paper.
If iodine is not applied, both the gram-positive and gram-negative stains will appear to be gram-negative. The iodine acts as a mordant that helps to fix the crystal violet stain in the gram-positive bacteria, making them appear purple. Without iodine, the crystal violet stain can be easily washed out of both gram-positive and gram-negative bacteria, resulting in a pink or red color.
Stain . Iodine is one.
The resultant crystal violet- iodine (CV-1) complex serves to intensify the-color of the stain. At this point, all cells will appear purple black.
Iodine work as a modrant which helps in fixing the stain properly by making a compled compoun of stain and cell wall.
Iodine is a purple-black non metal that changes to a deep purple gas when heated.