Essential Oils are vital elements of Plants. They considered to be vegetable hormones and they are extracted from varying part of the plant. As Example, Sandalwood Oil extracted from the tree, Neroli Oil extracted from the orange blossoms etc. True essential oils are very expensive to produce because distillation and extraction if very labor-intensive work.
Essential Oils appears in large quantity in the leaves of plants than they do in the petals. It is requiring above 400 Kgs of Parsley or thyme to produce 1 Kg of Essential oil. We we moved to essential oils extracted from petals, the quantity required multiplied by 10 times, so 4000 Kgs of rose petals are required for extraction of 1 Kg Rose Oil. Around 6 Tons of Orange blossoms to produce 1 Kg of Neroli Oil.
from : Organic Essential Oils