It grows to around 6 metres in height and bears clusters of pink or white flowers.

It is unusual amongst New Zealand's metrosideros species in that its branches display a weeping habit, forming a 'hanging curtain' appearance.

The name commemorates William Colenso, an early Cornish Christian missionary who was one of the great characters of New Zealand botany.

It is usual to find the vine form of rātā climbing up other forest trees, however Colenso's rātā is also partial to limestone cliff faces where it can climb cliffs relatively undisturbed.

However, it is in several ways superior to more commonly grown species, such as Metrosideros carminea, on account of the ordered appearance of its growth form, and the 'movement' conveyed by its downward arching branches.