Blue morning glory
Convolvulaceae (bindweed) family
Also known as
blue dawn flower, blue bindweed, blue convolvulus, morning glory, I learii, Ipomoea congesta
Where is it originally from?
Throughout tropical areas
What does it look like?
High climbing vine with tough, hairy, twining, running stems with tough fibrous roots without rhizomes. Leaves (5-18 x 5-16 cm) are usually 3-lobed and silky-hairy underneath. From late spring to early winter, groups of 3-12 deep blue-purple flowers that are pink at the base and wither in the midday sun are produced. Little or no seed is produced in New Zealand.
Are there any similar species?
Exotic species: Purple morning glory (I. purpurea) has violet-purple flowers (5-6 cm diameter), sets viable seed but is uncommon (only found in Napier, Christchurch and one site in the Bay of Plenty to date). Great bindweed (Calystegia silvatica) has long, extensive rhizomes, arrow-shaped leaves, large white flowers and is common, especially in Canterbury. Also similar is field bindweed (Convolvulus arvensis). Native species include: railway creeper (I. cairica, I. palmate) which has leaves divided into 5-7 finger-like lobes, mauve flowers 5-8 cm diameter, grows in coastal areas and is uncommon, pink bindweed or convolvulus (Calystegia sepium) which has extensive rhizomes, arrow-shaped leaves, flowers pink with white stripes, and is very common, shore bindweed (Calystegia soldanella) which is usually prostrate, has smaller, thick, semi-succulent leaves, 3-5 cm pink flowers, and is coastal, and Calystegia tuguriorum which has slender, much branched, climbing stems, roundish or kidney-shaped leaves, flowers white or pink, 4-6 cm diameter, and grows in lowland forest margins all over New Zealand.
Why is it weedy?
Very fast growth rate, longevity, dense smothering habit and ability to climb to top of high canopy makes this the dominant vine wherever it occurs. Tolerates hot to cool temperatures, and damp to dry conditions.
How does it spread?
Creeping stems spread this plant locally, and stem fragments are moved in dumped vegetation. Sources are gardens and wasteland.
What damage does it do?
Climbs over all other species, ultimately killing them. Can replace forest with low weedy blanket, and is the last species in many cases when a bush area totally succumbs to weeds.
Which habitats is it likely to invade?
Most warmer habitats except swamps and coastline.
What can I do to get rid of it?
Firstly establish that the species is not a valued native plant.
1. Hand pull, dig out roots (all year round). Dispose of roots and stems at a refuse transfer station or bury deeply.
2. Cut down and paint stump (all year round): glyphosate (100ml/L) or metsulfuron-methyl 600g/kg (1g/L).
3. Cut vines at waist height (summer-autumn) and spray foliage below: glyphosate (10ml/L + penetrant) or metsulfuron-methyl 600g/kg (2g/10L + penetrant (knapsack) or 20g/100L + penetrant (spraygun)). Follow up to check that slashed stems have not resprouted.
What can I do to stop it coming back?
Slashed stems resprout. Cut plant material can reprout. Eliminate from bush edges and dumps. Limited follow-up required.