|Weeds in our Area (Part One Hundred and Forty Seven)
By Bob and Ena McIntyre – Garden Route Region.
UPDATED LIST: Ipomoea indica & I. purpurea
Family Convolvulaceae (Morning glories/purperwinde)
In the early 1950’s the morning glories were promoted as an excellent plant for covering unsightly fencing, embankments and the walls of outbuildings. Its popularity was fuelled by enthusiastic descriptions such as “growing with cheerful abandon in almost any soil” and therefore perfectly suited for the above purposes. Also to the Ipomoeas advantage is the fact that they grow very quickly and are self-seeding. Clearly with so much going for it the recipe for becoming invasive was perfect. Ipomoea indica is known by several common names, including blue morning glory and blue dawn flower. It is a soft perennial vine native to Hawaii and the New World tropics. It is also found throughout the tropical and warm areas across the globe as an introduced species where it has in many places become naturalized and is often regarded as a noxious weed. In both Australia and New Zealand it has become an invasive species. Predisposed to moist and rich soil, it can and does grow in a wide array of soil types. Ipomoea purpurea, the Purple or Common Morning Glory, is native to Mexico and Central America.
Description: Ipomoea indica and I.purpurea are twining and climbing plants. I.purpurea is an annual and I.indica is perennial. In both cases the plants flower prolifically and make a stunning display of strong colour. The flowers are long and trumpet-shaped. Most commonly the colours are shades of purple-blue and white but there are also magenta and reddish varieties - sometimes with a contrasting stripe. In the warmer parts of the country the plants flower throughout the year. The leaves are heart-shaped and the stems are covered with brown hairs.
Invasive Status: These Ipomoeas have been reclassified from category 3 to category 1b in the updated list. The plants invade riverbanks, woodland, wasteland, arable land and coastal dunes – clearly justifying its classification as transformer. By virtue of its vigorous growth habits the morning glory vine simply outcompetes slower growing and less robust indigenous vegetation. Our country’s eastern areas and the coastal region all the way to Cape Town are the worst affected. NOTE: The plants along the lagoon verge in Wilderness are the indigenous Ipomoea cairica (Klimop). They have similar looking flowers but the foliage is very distinctly palmate (hand-shaped) as opposed to the heart shape described above.
Control: Registered herbicides are available for both species.
References: ALIEN WEEDS AND INVASIVE PLANTS: Lesley Henderson Copyright @ 2001 Agricultural Research Council. www.wikipedia.org and Una v.d. Spuy; Ornamental Shrubs and Trees for Gardens in SA.