|Morning glory - Ipomoea spp|
|In this issue we continue with our series of articles on exotic vines that impact on rainforest remnants around Brisbane. Another of the widespread and destructive vine species is Morning Glory (Ipomoea spp). There are several species of Morning Glory occurring around Brisbane. Five-leaved Morning Glory, or Mile-a-minute (Ipomoea cairica) is from tropical Africa/Asia. It is a weak twining climber and is easily distinguishable by its 5-7 lobed leaf (similar to the fingers of a hand) and pink-purple funnel shaped flower. As the name Mile-a-minute suggests, this vine and its related species are capable of fast growth given the right conditions. Five-leaved Morning Glory is usually seen on the rainforest edge where it can establish and capably grow over and smother tree saplings and understorey shrubs. This species of Morning Glory is especially common in coastal areas and can be a big problem in littoral rainforest remnants.|
The other species of Morning Glory commonly occurring in Brisbane’s rainforest remnants, Blue Morning Glory (Ipomoea indica) and Common Morning Glory (Ipomoea purpurea), originated from America. Both of these species are recognisable by their heart shaped, sometimes 3-5 lobed, leaves. However, Blue Morning Glory has large dark blue-purple funnel shaped flowers (in groups of 3-12 blooms) whilst Common Morning Glory has white – pink/purple funnel shaped flowers, in groups of 2-3 or as solitary blooms. It is hard to distinguish between the two when they are not flowering. Both of these vines are strong, twining climbers that can grow into the canopy of the rainforest. Their rampant growth can successfully form a curtain of stems, which is capable of destroying intact rainforest canopy. This is caused by a combination of
a) Inhibition of photosynthesis of the trees on which they are climbing and;
b) Breaking of branches by sheer weight and number of leaves and twining stems.
These two exotic vines are mainly found growing in heavily disturbed remnants and are largely confined to sunny edges and gaps
within the forest.
All locally occurring exotic species of Morning Glory produce seeds within globular capsules. Seed dispersal is by wind action and gravity. Ipomoea purpurea is known to also spread by vegetative means with the stems rooting at the nodes. The ornamental appeal of these exotic vines is obvious when they are in flower, indeed it would seem that most Morning Glory infestations have originated from garden plants that have escaped into local bush land. Rainforest remnants growing on moist alluvial soils (mainly along watercourses) seem most threatened by these vine species, mainly because weed growth is much more luxurious and rapid on these favourable sites. Some Morning Glory seed may also be transported (by floods and normal stream flow) to different rainforest sites along local waterways.
Control and eradication of the Morning Glories is (thankfully!) fairly straightforward and simple. Several methods can be used. Small infestations of stems can be cut and the roots dug out by hand. Larger infestations involving many stems can be dealt with by the cut and paint technique. Cut the vines at breast height; the upper growth can be left to die in the canopy. The basal stem should then be re-cut closer to the ground and a neat/100% (dilution of e.g.1:3 also suitable) glyphosate based herbicide (e.g. Roundup) should be applied immediately to the fresh basal cut (i.e. within 15 –20 seconds cutting). This technique is usually 100% effective on Morning Glory species. Any additional regrowth or vines growing on the forest floor can also be dealt with by foliar spraying with glyphosate (1:100 or 1:50 concentrations). Remember that any spray drift will harm native plants in proximity to the spray area.