Just back from the moringa collection to collect leaves for genetic analysis and seeds for micro-RNAs. Here are some photos of flowers, fruits, and other things from June and August in the collection. Lots of collection maintenance this month- planting new plants, erosion control moving grumpy plants to locations we hope they will like better. Hopefully lots more flowers and fruits to report next blooming season!
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Five months after Hurricane Patricia plowed directly over the Moringa collection, the plants are looking good. We lost about 30% of the plants that were planted out in the botanical garden, mostly the smaller ones. Some of the larger plants went dormant and are still leafless. Though they have never done this before, and have kept their leaves through the dry season sans hurricane, in general leaflessness is normal for this time of year, which is the height of the dry season. And like many plants of tropical drylands, Moringa species flower at the height of the dry season and shed their seeds just before the rains come. Despite the battering they took back in October, some plants are flowering for the first time here. Moringa oleifera, M. drouhardii, M. concanensis, M. stenopetala, M. rivae, and M. longituba have flowered before, but it’s the first time that we’ll have more than one M. longituba and more than one M. rivae in flower at the same time. I will be in the field when they open, but I am trusting humminbirds and bees to do the right thing. It would be the first time we get seed from these species from our own plants. Just as exciting, it’s the first time that M. borziana flowers in the collection (they nearly did in October/November, but Patricia blew all the buds off). Not only that, but it looks like three plants will bloom at the same time, so again fingers are crossed for seeds. Also, here are what as far as I know are the first photographs ever of Moringa hildebrandtii flowers, which I had never seen before. They are described in the literature as being slightly bilaterally symmetrical, but this is not really evident in these flowers. What is interesting and unique in the family is the long “claw” (the petal “stalk”), and the very short “limb” (the “petal” part of the petal). Not only is the limb short, but it withers and turns brown almost immediately after opening. The result is a vivid combination of yellows and browns in the floral display of Moringa hildebrandtii. Alberto’s Moringa oleifera experiment on the relationship between plant size, leaf area, and stem length got flattened in October and has come back nicely. He and Diana have started harvesting plants and have made excellent progress. Hopefully we’ll have a manuscript by the end of the year. Finally, a few photos of the plants in the collection plus some local animals, in this case an anole lizard Anolis nebulosus I think, which is common in the collection, plus some ibises, which I had seen in the area but never in the collection itself. If you take a sample from the trunk of a Moringa tree, you will see that the wood cells have starch, even the cells way in the center of the stem. Starch is the way that plants store the products of photosynthesis, so it’s a crucial energy reserve. Its presence in cells is usually taken as evidence that the cells are alive. For one thing, it would be wasteful to make the starch and then let the cells die without using it. For another, bacteria often degrade starch fairly quickly when a piece of wood dies, so it would be surprising to find starch persisting for very long. But these are just conjectures that need testing. Just how much of the trunk of a moringa consists of living cells is an important key to understanding how they can resist drought so well. Looking at the swollen trunk of one of the fat bottle tree moringas, like M. drouhardii or M. stenopetala, it’s easy to think that all that water storing trunk tissue is drawn upon to keep the plant going through drought. But the only way really to tell is by seeing whether the cells are alive and functioning or not. This is exactly what UNAM master’s student Matiss Castorena’s project involves. He is carrying out a comparative study to see how the amount of living tissue in trunks varies across species. To complement this study, he is looking in detail at how living tissue is distributed within a single large M. stenopetala tree. He has taken cores all around and the length of two trunks of the tree. He then takes these cores and incubates them in a solution of triphenyl tetrazolium chloride (TTC). The enzymes involved in metabolism reduce TTC to triphenyl formazan (TPF). The neat thing about this is that TTC is soluble but TPF is not only insoluble but is a deep red color. This means that very active living cells become markedly red, sluggishly metabolically active cells various shades of pink, and dead cells don’t change color at all. This means that along a core sample from the outside to the inside of the trunk, Matiss can map the distribution of metabolically active cells. This is important because only the living areas are involved in conducting water, and in storing and mobilizing photosynthetic products, both factors that are very important in plant functional aspects like supporting the leaves and resisting drought. What Matiss is finding is very interesting. It turns out that very little of the trunk is alive. Moringas seem to be just a thin layer of live wood overlain on a central core of dead or very metabolically sluggish cells. So those fat trunks, that would seem to be giant water tanks, might not be serving in storage as much as we think. Soon Matiss will be sampling our large Moringa drouhardii from our sap flow experiment, and this will help us to understand the data that those sensors gather. Keep up the good work Matiss! FundingOngoing fieldwork, collection maintenance, experiments, and laboratory work are being made possible by grant RT200515 of the Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica of the Universidad Nacional Autónoma de México
A member of the northeast African clade of Moringa, M. borziana is a remarkable dwarf species. It has a large underground tuber and one or two stems, which are usually just 1-2 meters tall. The species often flowers leafless, or just as it leafs out, such that the plants are in fruit by the time they are fully leafed out. The flowers are big, yellow, and probably bee pollinated. Only one is flowering at the moment, from the coastal dry tropical woodlands of eastern Kenya. They might not be self-compatible so getting seeds seems unlikely just yet, but this will only be a matter of time as the rest of the plants mature and they synchronize their flowering.
A major research milestone for the collection. The idea of the collection is to gather the widest diversity of Moringa germplasm in the world together in one place. Once this diversity is gathered, then it is possible to start answering our questions about moringa—what is the most nutritious species? Having identified the species, we can start looking for the most nutritious individual, or variety, or population of that species. We can compare the cancer chemopreventive agents across the members of the collection or their glucoregulatory activity. But we need the trees growing and healthy, and we need them large. We need them large to be able to harvest the leaves, flowers, fruits, wood, seeds, or whatever part needs study.
So, it was a major success that, just 7 months after the initial planting out, I was able to harvest leaf tissue from 55 individuals from 11 species plus one interspecific hybrid of Moringa representing 46 different localities or seed sources. I sent these samples to collaborator Renuka Sankaran, of Lehman College/ City University of New York. Renuka is a specialist in nutritional aspects of edible plants, especially protein and mineral nutrition. Along with her student Scott Macbeth, they will screen these samples to start looking for the “best of the best” Moringa in terms of nutrition. We’ll keep you posted on our findings. When not being used for food, oil, forage, medicine, water purification, fiber, or biofuels, moringas are often used as ornamentals. I will look at outdoor uses in another post. This post will look at small moringas as ornamentals in pots grown by people who like to look at tubers, roots, and other sculptural dryland plants. Dryland plants that grow with exposed tubers, or that can be grown with exposed tubers, are often known as caudiciforms or caudex plants, and fat, water-storing trees are known as pachycaul trees. They are both esteemed ornamentals. The most recent shipment of my moringa collections from Africa, Asia, and Madagascar just arrived from Missouri, where they have been under expert care for more than ten years. They will soon be planted out here at the collection and grow into trees or shrubs, and lose some of the charm that they now have. So it's a good time to take a snapshot of what they look like now to show what moringas look like when grown very "hard," that is, with very little water. You will never kill a moringa for lack of water. Keep them dry, only let them grow a few weeks a year, and you will be rewarded with a very fat-based, compact caudiciform. Most of the plants shown below are 10 years old from seed. By far one of the best caudiciform species is our old friend Moringa oleifera. Remember that this species is famous for growing into a 6-8 meter tall tree in a year. If you give it just a little too much water, it will shoot for the sky and you will lose the charming caudiciform shape. Keep them dry, though, and you will be rewarded with almost comical, often almost perfectly shperical fat tubers. Most oleiferas will do this-- the photo below includes street tree M. oleifera from India, from Madagascar, and the cultivar PKM. That M. oleifera is so easy to come by inexpensively, along with its tendency to form wonderful caudiciforms, leads several unscrupulous nurserymen to sell hard-grown oleifera seedlings posing as the rare northeast Africa dwarf species such as M. borziana or M. rivae. These are to my knowledge not in the nursery trade and probably represent M. oleifera. If you have doubts, send me photos and I can try to ID your plants. The pachycaul species Moringa ovalifolia also does well in a pot. It grows as a tuberous herb for many years before forming a permanent stem. This is a good pachycaul tree for a pot because unlike many pachycauls it gets a very fat base in a pot, looking like a miniature version of its wild self. Moringa peregrina, one of the slender trees, is one of the most exotic moringas when grown in a pot. A tree in the wild, it hangs on for years as a caudiciform when grown in a pot, dying back to perfect globby tubers when it gets dry. When watered, it produces blue foliage, unique in the family. Moringa longituba is a coveted species, with its fat tubers and red flowers. The tuber in the wild grows way below ground level and moringas don't like their roots kept warm, so they are not 100% happy with growing with the tuber exposed. They grow quickly enough from seed but as adults get long and rangy if given too much water. So, Moringa offers great material for growing as ornamental caudiciforms in pots. Just be sparing with the water and watch out for M. oleifera masquerading as other species. Happily, M. oleifera, the easiest species to get ahold of, is also one of the best species for culivation as a caudiciform.
In 1997-1998 I was in Toliara (Tuléar), southwestern Madgascar, to collect, among other things, Moringa drouhardii and to look for wild Moringa hildebrandtii. Moringa drouhardii is reasonably common in a variety of settings in southern Madagascar. I saw it growing in dry scrub south of Toliara on bare limestone hillsides, where, at maybe 4-5 meters tall, it was the tallest plant in the area. It also grew in dense tropical dry forest on the steep limestone slopes of the Onilahy River canyon. There the plants were taller, to about 7 meters tall. In southeastern Madagascar it grows in the Berenty area dry forest, which is relatively flat and rolling on deep soil. There the trees were about 6 meters tall. It also grew in the same general area but in the gallery forest at Amboasary along the Mandrare river. This is tall riparian forest on deep alluvial soil with plenty of moisture. There the trees were tall and relatively slender and at least 8 meters tall. In early 1998, all the plants were in flower. Given that Moringa oleifera flowers so quickly in cultivation, about 6 months, I was curious to know how long it takes the other species to get to flowering age. In Toliara town, I saw a Moringa drouhardii planted as an ornamental on the grounds of a hotel. It was in full flower, so I asked the gardener about the plant. He said he had planted the tree as a small seedling four years ago, and that this was the first time that it had flowered. So, four years to flower. I collected seeds of M. drouhardii in southeastern Madagascar and planted them in 1998 for my research. They grew well and the experiments also came out fine. Then the plants remained in pots, some in a greenhouse in Califorina, some in Missouri. There they survived nicely but the cool temperatures and limited root run kept them small, less than a meter tall. I brought them down to Mexico in 2000, and they remained in Mexico City outside in pots. Mexico City is at 2000 meters elevation and with its tropical highland climate it is always cool at night and can even freeze at the height of winter. So, not a good climate for moringas. Moringa oleifera simply refused to grow for me. I lost an M. longituba seedling to the cold, which bothered me considerably. The M. drouhardii, which is one of the species that best tolerates cooler temperatures, though, did hang on, growing a cm or two a year but never more. Finally, in 2010, I planted two individuals here in the coastal lowlands (see post on Moringa drouhardii in the ground). Now, four years later, just like in Toliara, M. drouhardii is in bloom! The four bottle tree Moringa species (M. drouhardii, M. hildebrandtii, M. stenopetala, and M. ovalifolia) have flowers that are very much unlike M. oleifera. Instead of being bilaterally symmetrical when seen from the front, they are more or less radially symmetrical. The flowers of the four bottle tree species are fairly similar. Here are photos of the flowers of M. drouhardii fallen on the ground here in Mexico. They have a powerful jasmine scent that you can smell from several meters away, perfuming the air around the trees. The flowers were perfumed during the day in Madagascar and were visited by bees, and here they are attracting bees and bumblebees as well. Here also is a photo of the flowers of Moringa stenopetala, which began flowering here in May and, with green fruits now developing, still has inflorescences in full flower. Moringa drouhardii and M. stenopetala flowers are distinguished by subtle differences. The easiest difference to see in these photos is that the petals of M. drouhardii have small “claws,” that is, have portions of the petals that are straight before reflexing. Moringa stenopetala petals, instead, are reflexed more or less directly without a claw.
With any luck, we’ll have seed of M. drouhardii soon, the first generation born and bred in the New World, from the seeds collected in Madagascar. After months of gathering my moringa collection, dispersed in Missouri and California, here in Mexico, and growing the plants up to 1-2 meters tall, last week I planted out the first 60 trees in the permanent moringa germplasm site. Different moringa species have different cultural requirements, so the site has a flat area of deep soil and is relatively moist, a shady hollow, and a hot, dry ridge. This combination is perfect for growing all members of the family. I planted out the giant species M. drouhardii and M. hildebrandtii along a shallow drainage in the area of deep soil. This will allow them to reach their full sizes--M. hildebrandtii can grow to 25 meters tall when growing in shady river bottom country, as I have seen along southwestern Madagascar’s Onilahy River. I planted M. concanensis and M. concanensisXoleifera on the drier parts of the flat area, and along about 60 meters of the egde of the property I planted a bunch of different M. oleifera plants to serve as a living fence. On the dry, exposed ridge I planted some M. peregrina and M. ovalifolia to see how they do, but they might require soil amendment because they like very well-drained soil. We’ll see what happens. The shady hollow will be stenopetala gulch. This small drainage has some intact bits of native woods on it, and in the gaps I planted about 20 Moringa stenopetala plants of various provenances, including seedling from trees I collected in the wild on Parmalok Island in Kenya’s Great Rift Valley. Most M. stenopetala plants in cultivation are probably not from wild plants but from cultivated ones in northern central Kenya and southern Ethiopia, where they are grown for food. In the wild, M. stenopetala seems to grow near water, and can get a very massive single trunk. In cultivation, they often grow into giant bushes. I am hoping that growing up among other trees, the ones I just planted will look more like the wild trees, with a single fat trunk. We got water to the site! The municipal water system doesn't reach the site, so we collect water in a cistern and then pump it via a 1hp electric pump to the water tank on the hillside. It's 250 meters and a 30 m elevation difference, so I am very impressed with the pump. The system seems to be working like a charm. Getting water to the site was a major triumph because getting the plants through their first dry season or two is all about water. Once they are established, they won't need any supplemental watering, but to get the plants going there is not botanical garden without water. I’m giving the trees a month to see how they do. The rains have started, which means that the weeds will be growing. Between the weeds and the leafcutter ants, being a small tree in the dry tropics can be daunting. But moringas grow fast and my bet is that in a month’s time, which is when I will evaluate the success or failure of the first planting, the trees will be established and growing at the usual shockingly fast moringa pace.
When your livelihood depends on plants, nitrogen is an obsession. A little nitrogen can make all the difference between a sapling that barely hangs on year after year and a vigorous, healthy tree that strikes its roots deep and firmly into the ground and bears abundantly year after year. So it's no wonder that a lot of people ask if Moringa can fix nitrogen. The short answer is no. If you want my random speculation on why so many people seem to think it does fix nitrogen, and why it would be so nice if it could, then read on.
No posts for a while as I have been working on the new shadehouse. Getting anything done in a remote little Mexican town takes a long time, but things are coming along and the moringas are loving the climate. Many moringa species stay very small for a long time, and need a very protected environment to keep them from getting stepped on, lost, or eaten by something. Even for medium-sized saplings of the larger species, it's very helpful to have a sanctuary. Leafcutter ants can set a small plant back with just one night's activity, not to mention marauding dogs, coatimundi, kids, or the village drunk nesting for the night. The shadehouse is located on a hillside so will get maximal light, even as the trees below grow. It is about three by nine meters and has a bed of native soil for growing plants directly in the ground. Next, the benches and the beds!
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AuthorDr. Mark E. Olson is a researcher at Mexico's national university and an expert on the biology of the genus Moringa Archives
November 2018
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