We will first head towards Etang-Salé on the Western coast; this is a semi-dry forest so you will not need the mosquito repellent compulsory in wetter areas. What we are looking for is a rather modest vine belonging to the Fabaceae or Leguminosae family. Abrus precatorius is a woody climber which grows between 1 and 4m (3 to 12 feet). There are two subspecies; Abrus precatorius subsp. precatorius which comes from tropical Asia, Australia and the Pacific and Abrus precatorius sbsp. africanus which obviously originates in Africa, Madagascar and Indian Ocean islands, and the differences are rather small.
Depending on the part of the world it is called ‘grain d'église', ‘liane réglisse', ‘graine diable', ‘cascavelle', ‘jequirity', ‘jumbie beads', ‘crab's eyes', ‘rosary pea'. It is usually found in fallows and forests, growing on sandy or rocky soils, in full sun to partly shaded exposure. The leaves are composed of eight to seventeen pairs of leaflets, the flowers come in dense clusters with a corolla pink to crimson. They are followed by oblong pods which split open when dry and reveal the showy seeds. Those persist for a long time in the pod and have a very decorative effect; they are spherical in shape and brightly colored, half black and half scarlet. This decorative feature is put to use in many countries where the seeds are used as beads for necklaces, bracelets and many ornaments. The trouble is that they also have deadly features, half a seed will kill an adult person if ingested because it contains abrin which is a very poisonous toxic related to ricin found in Ricinus communis (castor-oil plant). Symptoms of abrin ingestion include respiratory troubles, fever, nausea, intense sweating, bloody urinating and low blood pressure. Soon the kidney, liver and spleen will stop working thus leading to death, and there is no antidote so my advice is, stay away from it!
Let us turn to a less dramatic species although it also has the benefit of producing round bicolor seeds but those are perfectly harmless. A common weed in tropical countries where it can be found along paths, sugarcane fields, root crops, vegetable gardens. Cardiospermum halicacabum or Cardiospermum microcarpum is known as ‘poc-poc', ‘ persil sauvage', ‘heart seed', ‘balloon vine', ‘wild parsley' or ‘calthrops', various names which depict it quite well. ‘Persil sauvage' which precisely translates as ‘wild parsley' clearly illustrates the fact that the leaves do resemble those of parsley, bright green and dissected. ‘Heart seed' is the vernacular translation of the genus name ‘cardiospermum' which indeed fits, since the white spot on the black seed has the shape of a heart, at least the kind of heart you see carved on trees if not the exact anatomical shape of a human heart!
Botanically speaking this spot is called the hilum. ‘balloon vine' evocates the inflated papery capsule which contains the seed, it will do a noise quite close to ‘poc' if stepped on or crushed between the hands. Flowers are real tiny, with white petals. This plant is not grown except maybe by some collectors and though the ‘balloons' may have some decorative effects they are not that great. The last information to give is that the ‘poc-poc' belongs to the Sapindaceae family, which better known members are the litchi tree and longan tree, both bearing delicious fruits.
The next vine to attract our sight is definitely showier and sometimes grown as ornamental while it can also be a weed in many tropical areas. The large yellow corolla with a deep purple heart is a way to brighten up some fence or wire mesh, the large heart-shaped deep green leaves will soon cover any support and act as background to display the flowers. Ipomoea ochracea is also known as Convolvulus ochraceus and most probably originates in Africa. It is indeed quite frequent in tropical Africa as well as in Central America, it has also been spotted in New-Caledonia and of course on Reunion Island. This perennial has climbing or trailing habits and is usually seen at low altitude by roadsides, fallows and bushes. It is not particularly sought after although yellow flowered morning glories are not that common, actually I have been ordered twice by a Japanese seed company several thousands seeds of this plant, so there must be something after all! Note that it is also attractive to bees and butterflies.
Now a much better known plant, one of the very numerous passionflowers. Indeed, members of the large Passifloraceae family are nowadays familiar with many gardeners and glass-house amateurs. Those plants not only display sophisticated flowers which give at once a very exotic touch to any garden but they also provide us with a choice of delicious fruits. Nonetheless the one we are taking a closer look at is probably still a rarity amongst collections and rarely grown. Passiflora maliformis (synonym P. ornata) can be found throughout the West Indies and South America where it is known under local names such as ‘sweet calabash', ‘granadilla de monte', ‘pomme calebasse', parcha cimarrona'. On Reunion it is know as ‘coque en fer' which means ‘iron shell', this refers to the fruit which is round and very hard--you may need a stone or a hammer to crack it open unless you have a muscular jaw and tough teeth. The plant itself will be found in secondary forests, along tracks and in abandoned lands, vining its way up to 6m high with a vigorous woody basis covered by grooved bark. The leaves are quite large, up to 25cm long, spear shaped. The flowers are pendulous, fragrant, with green petals mottled purple or brown red. The attractive part of those flowers come mostly from the large corona filaments (up to 30 mm long) banded white and purple and the large pale green bracts which act like a casket in which the flower is displayed.
The last species to be admired on this tour will bring up back uphill where it is often seen decorating garden entrances, trellises, fences and bushes it can cover easily. Native from South Africa hence one of its vernacular name of ‘Natal ivy' this decorative and easy to grow vine is not really an ivy although the shape of its leaves may induce you in thinking so. Senecio mikanoides, also called ‘climbing senecio' or ‘parlor ivy' belongs to the Asteraceae family, a pretty large one as it numbers some 1535 different genera amongst which the Senecio genus itself has no less than 1500 species. Many of them have evolved adapting to harsh environment and several succulents are commonly grown. Senecio mikanoides (syn. Delairea odorata) has fleshy leaves and pale yellow scented ray-flowers, it is seen here and there in gardens and has escaped in the wild in different places such as Australia, Tasmania, California as the tiny seeds are carried by the wind through the help of small egrets. Propagation by cuttings or layering is quite easy. It will grow in different kinds of soils and can stand some dryness. There is also a variegated form sold in nurseries.Although this is already the sixth article concerning vines growing on Reunion island we have but brushed the subject as vines are an important part of tropical plants so we certainly will have a few more strolls through gardens and forests of the island