Common name: Tube flower

Tube flower is a flowering shrub native to Southeast Asia, its natural range extending from Singapore, through Indonesia, to the Philippines.

It is fast-growing and may attain heights of up to 5 m (16 ft), though it is more typically 2 to 3 m (7 to 10 ft) tall with multiple stems in a V-shape, forming a wide-spreading crown, nearly as wide as the plant is tall. The stems are soft-wooded and covered with light grey bark that is either smooth or has raised wart-like pores.

The leaves are large, oval, glossy green and deeply veined. In the dry season, they fall off the tree to conserve moisture, with the new leaves starting to emerge soon after.

The flowers are long, thin white tubes borne in showy clusters that bloom on and off throughout the year. However, they are most abundant from spring to late summer, coinciding with the rainy season. Each flower sits in a green calyx that swells after the flower falls, becoming fleshy and brilliant red. It then unfolds into a star shape with a small, round, blue marble-like fruit set in the centre.

Use

It is cultivated for its showy flowering and fruiting display and is a typical home garden and landscape shrub in South Florida. The stems are occasionally pruned to create a small, single-stemmed tree. Butterflies are attracted to the nectar-rich flowers. The wood has little value because it is soft and weak.

Climate

Grows naturally in humid tropical lowland climates, generally areas with annual lows of 18 to 25°C, annual highs of 27 to 35°C, annual rainfall of 1200 to 3500 mm and a dry season of 5 months or less.

Growing

New plants can be started from seed, cuttings or using air-layering (circumposing) methods. Performs best on free-draining, rich loam and sand soils of a slightly acid to neutral nature, generally with a pH of 6.0 to 7.5 and on sites with full sun to light shade exposure.

Problem features

There does not appear to be any reports of it as a weed or invasive species, despite its introduction into areas outside of its native range. It is prone to suckering from the roots, especially after the plant is pruned or somehow damaged.

Books

• Barwick, M., et al. 2004, Tropical & subtropical trees : a worldwide encyclopaedic guide, Thames and Hudson, London

• Macmillan, H. F. 1943, Tropical planting and gardening : with special reference to Ceylon, 5th ed, Macmillan Publishing, London

• Menninger, E. A. 1962, Flowering trees of the world for tropics and warm climates, 1st ed., Heathside Press, New York