(Editor's Note: This article was originally published on June 1, 2008.)
Although all are not exactly morning glories they all belong to the same botanical family, the Convolvulaceae. This quite large family comprises over 55 genus and 1650 recorded species through the world (the amount of still not recorded and yet disappearing species being larger every day...) Some 44 species of 11 different genus have been recorded on the Mascareignes archipelago, Reunion being one of the islands of the Mascareignes. Plants of the Convolvulaceae family are characterized by a creeping or climbing growth and when climbing they are voluble which means the stem will twin around any available prop. The flowers usually have trumpet shape with a very wide range of colours.
Let us start with a useful one whose tuberous root is highly edible: Ipomoea batatas is the yam or sweet potato. Originating in tropical America it is nowadays grown in all tropical countries and a very important food crop in Africa. Horticulturists have created new varieties with purple or variegated leaves. It is a quite handy ground cover as it will be more a creeper than a climber.
Another Ipomoea has great decorative effect and makes a good conversation point at aperitif time as it blooms when sun sets. Ipomoea alba is a night bloomer which will stay open all night and fade in the early morning. It not only displays large flowers up to 15 cm across, pure white and with a nice perfume, but the opening of the corolla takes place within a few minutes and looks like some speeded-up motion.
Many other Ipomoea grow throughout the island such as I. purpurea and I. indica which both display flowers going from deep purple to pink, a common weed in most tropical countries but with great effect when grown on wire fence. Ipomoea ochracea is one of the few yellow flowering morning glories, displaying a purple-black heart. Ipomoea coccinea has small but very numerous bright red flowers and a natural mutation with orange flowers has been recently discovered by the author of this article. Orange flowers are quite rare in the family and several generations of the plant have been grown to make sure the genes are fixed. Ipomoea pes-caprae or the "beach morning-glory" is found or most tropical beaches world-wide where it helps fixing sand, a typical salt-tolerant species (halophilous).
Let us switch to a different genus within the family. Merremia has six species growing here, Merremia tuberosa is the "wooden rose," a huge vine growing easily up to 15 meters that produces bright yellow flowers which will become highly prized for bouquet making once dry, looking just like carved flowers. Merremia umbellata will not produce such flowers, but still has an interesting feature as it blooms in clusters (an umbel is a kind of flowers group) with nice yellow flowers. Merremia peltata is another huge monster which can reach 30 meters long and fully cover trees and shrubs. It has a white to yellow corolla and rather larges leaves (up to 30cm long and wide).
We can also enjoy at this time of the year the blooming of Argyreia nervosa known in the U.S. as Hawaiian baby wood rose, though it is not from Hawaii but from India and it does not look in shape nor in colour like the wood rose. It has light purple flowers with a darker heart and the leaves have a silver hair cover on the underside; hence the local name of ‘liane d'argent' (silver vine). It is another monster plant which will soon cover both your garden and house, provided you live in tropical climate.
Another plant traditionally used by tribes of Southern America is Rivea corymbosa (syn. Turbina corymbosa) and known in Mexico as ‘lococito' or ‘small crazy' because of the seeds' potency. It displays clusters of white flowers and is reported as being attractive to bees.
Now a real jewel, Stictocardia tiliifolia from eastern tropical Africa has sumptuous pink to purplish pink flowers with purple heart and yellow strikes along inner chalice. This one is found only in gardens on Reunion but has escaped in the wild in both Mauritius and Rodrigue island.
And the last one is a parasitic species which is a rather rare feature amongst vines. Cuscuta campestris is a weird one, lacking chlorophyll hence its yellow colour, and also lacking leaves (which actually are reduced to scales) which is the reason why it has to take sap from host plants, absorbing it through special sucking devices, a real Dracula plant!