Convolvulus waitaha

Convolvulus waitaha is a perennial herb in the family Convolvulaceae. The stems can reach a length of up to 800 millimetres (31 inches), which may be covered with hairs. Leaves are found in a rosette arrangement. Leaves are arranged alternately on the stems and measure 6–17 × 5–12 mm long. They range from triangular to oval or broadly oblong in shape and are green in colour. The leaf surface is usually smooth. Leaf edges are smooth to slightly wavy. The pedecils are 8–18 mm long. The sepals are 3.6–4 × 2.1–2.6 mm long. The flowers are white, about 10–16 mm wide when open. The centre of the petals is pale green. The fruits are found in seed capsules which are 5–6 × 5–6.5 mm long, and contain two to four seeds. The seeds are 3.1–3.9 × 2.3–3.3 mm long, and brown to greyish in colour. C. waitaha has a diploid chromosome count of 22.

Convolvulus waitaha is endemic to New Zealand. Its range sporadically covers the eastern North Island and South Island. There is a historical record of the plant being present in Hawke's Bay. C. waitaha is found in numerous localities along the Cook Strait. In the South Island, C. waitaha is found from the Marlborough Region south to Otago. Its 2023 assessment in the New Zealand Threat Classification System was "Not Threatened".

Habitat. Convolvulus waitaha is found in coastal to lowland environments, reaching 500 m (1,600 ft) above sea level at maximum elevation. It is found in various habitats, including tussock grasslands, browsed pastures, banks, rocky slopes, and gravelly areas.

The members of the Convolvulaceae are primarily pollinated by insects. The seeds of C. waitaha are dispersed by the wind.

The etymology (word origin) of C. waitaha's genus name, Convolvulus, comes from the Latin convolvere, meaning "to twine around". The specific epithet (second part of the scientific name), waitaha, is a Māori language word meaning 'backwater'. It comes from wai, meaning 'water', and 'taha', meaning "to pass to one side". The species is commonly known as grass convolvulus.