The name Metrosideros means “iron-hearted” (from the Greek metra= middle and sideros = iron referring to the hardness of the timber, umbellata meaning “bearing umbels” an umbrella-shaped group of flowers originating from a single stem.

This is a shrub or tree up to 15 m tall or more that starts off on the ground. The trunk grows up to 1 m or more in diameter and is covered in a pale papery bark that peels off in strips. Southern rata has long pointed leaves that are very shiny on the upper surface. The leaves are longer than those of the Northern rata, but more closely resemble Northern rata than pohutukawa. The young foliage is a pleasing brown or purple in colour and the tree puts on a spectacular display of crimson flowers. An occasional yellow-flowered specimen can be found in Otira and Westland. Young leaves and branchlets are silky to the touch. The seed capsules are bigger than those of Northern rata. The timber is very similar to that of Northern rata and used in the same way.