Also known as gumdiggers soap, kūmerahou is a native shrub endemic to the top half of the North Island. Both of its names are wonderfully descriptive; the leaves of the plant can be crushed with water and will lather up when rubbed - pioneer gumdiggers used it to wash sap off their hands. The name kūmerahou, which is a mistaken spelling of the Māori words kūmara hou - literally fresh or new kūmara, relates to the fact that Māori planted their kūmara crops when the kūmerahou began flowering.
Kūmerahou has beautiful bright yellow flowers in spring, which are attractive to native insects. It grows well in full sun and on poor soil, including clay. It used to be a common plant on road cuttings, but in recent times has been out-competed by introduced weeds. Kūmerahou is a great replacement plant for cottoneaster (Cotoneaster glaucophyllus) - which is an unwanted weed in Kaipātiki.