Helmholtzia is a small genus of three species – two occur in eastern Australia and the third is found in New Guinea and Indonesia. They are rhizomatous perennial plants found in wet, tropical environments.
Helmholtzia glaberrima has dark-green leaves arising from an underground rhizome and forming a robust clump 1.5 to 2 metres high and wide. The linear-shaped leaves are about 7 cm wide. Tall spikes about 70 cm long and composed of numerous white or pink flowers are seen in spring and summer.
Stream Lily has been in cultivation for many years. It is a hardy plant for tropical to temperate climates in a semi-shaded location in moist soils. It is tolerant of moderate frosts. If necessary the plant can be cut back severely and it will regenerate from the rhizome.
Propagation may be carried out from fresh seed which does not require pretreatment. Division of established clumps is also possible.
Photo: Brian Walters