Moringaceae are woody, often quite stout-stemmed shrubs or slender trees. They reach about 10-12 m (30-36 ft) in height. Their leaves often smell unpleasant when crushed. These leaves identify the Moringa genus: they are 1-to-3 compound spiral and deciduous, with conspicuous nectaries at the articulations and at their base. The creamy-white papilionoid flowers, polysymmetric to strongly monosymmetric, show five petals and five stamens.
They give rise to long, slender, tricarpellate, three-angled, capsular fruits.
Native only to restricted parts of the southern foothills of the Himalayas, M. oleifera is cultivated in most tropical countries. Moringa oleifera is a robust species. As a relatively short plant, an advantage under such severe conditions, it can withstand and survive both severe drought and mild frost.
50-year old Mark E. Olson, Californian from the Sierra Nevada in origin, professor of plant biology at the Universidad Nacional Autonoma de Mexico in Mexico City, became a propagandist for cultivation of the Moringa tree, for its wide array of benefits, nutritional and medicinal — more on that later. The Olson’s love affair for the Moringa began in 1995 when he started work on his Ph. D., completed in 2001 at Washington University in St. Louis. It turned into his main vocation in life, to find Moringa tree species wherever they grow, to describe them and record the findings. Since the 1990s, Olson spent nearly two decades collecting the seeds of the genus’s thirteen known species, travelling throughout Southeast Asia, the Middle East, and Eastern Africa, i.e., in hot and dry climates, those where Moringas thrive.
The different species of Moringa are easily separated, each is “as strikingly distinct as the other Moringa species are from each other”. Given such diversity in this whole genus, I am enclosing here their mini-portraits. Bottle-tree shaped, two species live in Madagascar. M. drouhardii’s bark is used for treating colds and coughs. It grows in scattered stands that can number hundreds of individuals, usually on limestone. M. hildebrandtii, a handsome tree that can grow 20 m-tall, is planted as ornamental, as a traditional cure-all, and to mark special occasions.
Another two bottle-tree species are from Eastern and Southern Africa. M. stenopetala is a crop plant cultivated in southwestern Ethiopia. Its leaves are covered with glistening nectaries. Found from southwestern Angola to central Namibia, M. ovalifolia is nicknamed the ‟ghost tree‟ from its bloated white trunks standing out on otherwise bare hillsides.
In the same group of slender trees as M. olifeira, Olson described another two species. M. peregrina is a native of the Red Sea region. With pink flowers, adult trees have a wispy look. M. concanensis has a very strong central trunk covered with an extremely distinctive layer of very furrowed bark that can be more than 15 cm thick!
The Horn of Africa hosts the remaining eight Moringa species, trees, shrubs and even herbs. M. arborea, M. longituba, M. rivae, and M. ruspoliana coexist in the extreme northeast of Kenya. Olson terms M. arborea ‟a very beautiful tree, especially when covered with its large sprays of pale pink and wine red flowers.‟ Two species, M. pygmaea and M. arborea, have only been seen twice each. M. borziana, found from southern Kenya to southern Tanzania, grows a shoot 3 m-high in two months. M. rivae occurs in Kenya and in southeastern Ethiopia as large shrubs up to 3 me tall with greatly swollen roots. M. ruspoliana occurs from northern Somalia to southeastern Ethiopia. It displays the largest flowers in the genus, up to 3 cm-long. Likewise, it has the largest leaflets in the genus, reaching 15 cm in diameter.
Those are also the thickest and toughest leaflets in the Moringa family. Echoing its Indian origins, the name Moringa comes from the tamoul language. The M. oleifera tree goes also by a number of nicknames, such as Drumstick tree — alluding to the trigonal shape of the fruit —, or horseradish tree — the roots can be made into a horseradish-like condiment ; it is now touted on the Web as the miracle tree. I think of it as a medicine-chest tree, for the wide diversity of the ailments its parts are believed to be effective for and used against. The best authenticated are cancer prevention, the leaf extract is antiproliferative and antimetastatic, effective as a complement to radiotherapy, in pancreatic cancer in particular ; and antibiotic activity.
As food, low-income groups in various countries, in East Africa in particular, use its leaves, flowers and fresh pods as vegetables, providing them with proteins, amino acids, fatty acids, vitamins and minerals.
Another asset of the M. oleifera plant is presence in the seeds of a cationic polyelectrolyte, put to use in clarifying otherwise turbid drinking water, by flocculating solid suspended impurities.