Ipomoea indica (Blue Morning Glory)

Scientific name

Ipomoea indica (Burm.) Merr.

Synonyms

Convolvulus acuminatus Vahl; Convolvulus congestus (R. Br.) Spreng.; Convolvulus indicus Burm.; Ipomoea acuminata (Vahl) Roem. & Schult.; Ipomoea cataractae Endl.; Ipomoea congesta R. Br.; Ipomoea insularis (Choisy) Steud.; Ipomoea leari Paxton; Ipomoea learii Paxton; Pharbitis insularisChoisy

Common names

Blue dawn flower, blue dawn-flower, blue dawnflower, blue morning glory, blue morning-glory, blue morningglory, common morning glory, convolvulus, dunny creeper, Lear's morning glory, morning glory, ocean blue morningglory, oceanblue morning glory, oceanblue morning-glory, oceanblue morningglory, purple morning glory, purple morningglory.

Family

Convolvulaceae

Origin

The origin of Ipomoea indica is unclear as it appears to be pan-tropical.

Naturalised distribution (global)

Locations within which Ipomoea indica is naturalised include the coastal districts of eastern Australia, southern Europe, southern New Zealand, southern USA, Pacific islands and eastern and southern Africa.

Introduced, naturalised or invasive in East Africa

Ipomoea indica is cultivated in gardens in Kenya, and the north-eastern corner of Tanzania and in Uganda. It has since become naturalised in all three countries.

Habitat

This species inhabits wetter tropical, subtropical and temperate regions. It is particularly common in suburban gullies, gardens, along roadsides, in riparian zones (banks of watercourses) and in disturbed rainforest. Ipomoea indica invades woodland, degraded land, arable land, roadsides, riverbanks, coastal dunes.

Description

A long-lived (perennial) twining climber growing up to 15 m high, but sometimes scrambling over low vegetation or creeping along the ground.

The stems usually develop a twining habit although they occasionally spread across the ground (they are sometimes prostrate). These stems are fairly densely covered in spreading or backwards-curved (retrorse) hairs when young and they occasionally also exude a white milky sap when broken.

The alternately arranged leaves (5-18 cm long and 3.5-16 cm wide) are borne on stalks (petioles) 2-18 cm long. They range from heart-shaped (cordate) to obviously three-lobed and have pointed tips (acute apices). Both leaf surfaces are softly hairy, the undersides more so.

The funnel-shaped (tubular) flowers are bright blue or bluish-purple in colour with a paler pink or whitish-pink central tube. These large flowers (5-10 cm long and 7-10 cm across) are borne in clusters of two to twelve in the leaf forks (axils). They have five long and narrow sepals (14-22 mm long). Flowering can occur throughout the year.

The fruit are globular papery capsules (about 10 mm across) containing four to six dark brown or black coloured seeds.

Reproduction and dispersal

Ipomoea indica reproduces primarily from broken fragments of stems that produce new roots at the nodes. Hence a common mode of dispersal is believed to be as a consequence of gardeners dumping unwanted vegetative material. It may also be dispersed by vehicles.

Similar species

Ipomoea indica is very similar to Ipomoea cairica (coastal morning glory), Ipomoea purpurea (common morning glory) and Ipomoea hederacea (ivy-leaved morning glory). These species can be distinguished by the following differences:

  • I. indica has hairy (pubescent) younger stems and heart-shaped (cordate) or three-lobed leaves. Its flowers are relatively large (7-10 cm across), its sepals are long and thin (14-22 mm long), and it does not produce viable seeds (capsules are generally not seen).
  • I. cairica has hairless (glabrous) stems and five to seven lobed leaves that resemble the fingers of a hand (They are palmately lobed). Its flowers are relatively large (5-8 cm across), its sepals are relatively short (4-7 mm long), and it often produces capsules containing four hairy seeds.
  • I. purpurea has hairy (pubescent) younger stems and heart-shaped (cordate) or three-lobed leaves. Its flowers are relatively large (3-7 cm across), its sepals are moderately long (10-15 mm long), and it often produces capsules containing six hairless seeds.
  • I. hederacea has hairy (pubescent) younger stems and heart-shaped (cordate) or three-lobed leaves. Its flowers are relatively small (3-5 cm across), its strongly curved sepals are long and thin (about 20 mm long), and it often produces capsules containing four to six hairless seeds.

Economic and other uses

Ipomoea indica has been widely cultivated as a garden ornamental. However, this cannot compensate for this plant's overall negative impacts.

Environmental and other impacts

Ipomoea indica regenerates prolifically and tends to outcompete indigenous vegetation, especially in disturbed areas and degraded land.

It has been listed as a noxious weed in some states in South Africa (prohibited plants that must be controlled. They serve no economic purpose and possess characteristics that are harmful to humans, animals or the environment) and as a Category 3 invader in others (no further planting is allowed - except with special permission - nor is trade in propagative material. Existing plants must be prevented from spreading) in others and a noxious weed in New South Wales, Australia.

Management

The precise management measures adopted for any plant invasion will depend upon factors such as the terrain, the cost and availability of labour, the severity of the infestation and the presence of other invasive species. Some components of an integrated management approach are introduced below.

The best form of invasive species management is prevention. If prevention is no longer possible, it is best to treat the weed infestations when they are small to prevent them from establishing (early detection and rapid response). Controlling the weed before it seeds will reduce future problems. Control is generally best applied to the least infested areas before dense infestations are tackled. Consistent follow-up work is required for sustainable management.

Plants can be hand pulled and the roots dug out roots (all year round). Roots can be buried deeply and the remaining plant material left to rot down on site.

Plants can be cut down and stumps painted with a suitable herbicide. When using any herbicide always read the label first and follow all instructions and safety requirements. If in doubt consult an expert.

Slashed stems resprout so there must be follow up and retreatment as necessary to ensure that long term control is achieved.

The editors do not know of any biological control programmes targeted at this species.

Legislation

Not listed as a noxious weed by the state or governments in Kenya, Tanzania and Uganda.

References

Global Compendium of Weeds. www.hear.org/gcw. Hawaiian Ecosystems at Risk Project. Accessed March 2011.

Henderson, L. (2001).  Alien weeds and invasive plants. A complete guide to declared weeds and invaders in South Africa.  Plant Protection Research Institute Handbook No. 12, 300pp. PPR, ARC South Africa.

Lazarides, M., Cowley, K. and Hohnen, P. (1997). CSIRO Handbook of Australian Weeds. CSIRO Publishing, Collingwood, Victoria.

Editors

Agnes Lusweti, National Museums of Kenya; Emily Wabuyele, National Museums of Kenya, Paul Ssegawa, Makerere University; John Mauremootoo, BioNET-INTERNATIONAL Secretariat - UK.

Acknowledgments

This fact sheet is adapted from The Environmental Weeds of Australia by Sheldon Navie and Steve Adkins, Centre for Biological Information Technology, University of Queensland. We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) - Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).

Contact

BioNET-EAFRINET Regional Coordinator: eafrinet@africaonline.co.ke