Exodus 30 gives a formula: stacte, onycha, galbanum and pure frankincense, in equal parts, beaten small, salted, and burned before the ark. The rabbinic tradition adds that the temple compound ran to eleven ingredients rather than four, and the Talmud preserves both the list and the family who held the recipe.
Galbanum is the awkward one. It is the gum resin of Ferula species from Persia and Central Asia, and by itself it smells green, bitter and slightly rank, which nobody disputes. The tradition does not treat this as a defect to be explained away. A well known homiletic reading takes the presence of a foul-smelling ingredient in the incense of the sanctuary to mean that a fast of the community which does not include its sinners is not a fast of the community, and the point is made from the incense rather than illustrated by it.
That is an unusual thing for a ritual recipe to be doing, and it is why galbanum keeps appearing in commentary far out of proportion to its importance as a material.
In perfumery the same quality is an asset. Galbanum is a classic green top note, sharp and vegetal, and it is the opening of several twentieth century perfumes that were built to be bracing rather than sweet. Perfumers describe it in almost the same words the Talmud does.