Myrrh is the aromatic resin of a number of small, thorny tree species of the genus Commiphora, which is an essential oil termed an oleoresin. Myrrh resin is a natural gum. It can also be ingested by mixing it with wine.
Myrrh gum, like frankincense, is such a resin.
When people harvest myrrh, they wound the trees repeatedly to bleed them of the gum. Myrrh gum is waxy, and coagulates quickly. After the harvest, the gum becomes hard and glossy. The gum is yellowish, and may be either clear or opaque. It darkens deeply as it ages, and white streaks emerge.
Myrrh is also found in the Christian Bible as one of the three gifts the wise men presented to baby Jesus.