Black Vetiver - Chrysopogon nigritanus

C. nigritanus on a flood plain in northern Ghana

More on Chrysopogon nigritanus.  I have continued investigations into this species of vetiver - common name ”Black vetiver”. It is found in nearly all sub-saharan African countries generally in association with river flood plain and seasonally flooded areas. For example the peripheral  areas of the Kafue River flats in Zambia, and the flooded areas of the Niger and Senegal rivers of West Africa. Its main uses include medicinal, freshening drinking water, thatch, handicrafts, forage (when young after burning), and farm boundary marking.

It appears only to propagate naturally from seed in these permanent/semi-permanent waterlogged areas.  Outside of such areas seeds either do not germinate or die after germination, and if used domestically the plant is propagated through slips.

The species appears to be retreating. Tony Cisse who farms near Dakar, Senegal only grows C.zizanioides descended from Chris Juliard’s importation (ex South Africa) initiative (1990s). He writes "Traditionally the most common use for C.nigritanus in Senegal has been for the roots that are added to drinking water. This is the common way people recognize the plant and its name in local languages. Whereas it would seem logical that it should be grown locally, there is now very little evidence of this. Vetiver roots are imported from neighboring Mali, and sold in small bundles. I have heard it was used in the past (possibly over 60 years ago or more) to demarcate fields, but I have never seen nor heard of it growing naturally, at least in the western areas of Senegal.  Reasons for this are likely to be associated with climate change and the drop in annual rainfall. There are very few areas that can be designated as flood plains, and standing water and ponds are generally very rare if they exist for more than a few weeks at most during the rains, and so this could account for this absence, although still present in Mali. The water table in much of Senegal is below the reach of vetiver roots. It is possible that there are parts of Eastern or northern Senegal along the river where the right conditions for C. nigritanus exist, but I have not been there to observe".  In Nigeria and other African countries, where new dams have been constructed, the downstream flood plains are no longer flooded and wild vetiver seems to be a diminishing component of the ecosystem.

C. nigritanus hedgerow for erosion control - Mambila Plateau Nigeria

Sterile non invasive C.zizanioides remains the preferred choice for all Vetiver System applications. Even though Nigerian research does support C. nigritanus for erosion control and phytoremediation applications note C. nigritanus has NOT been tested for steep slope stabilization and virtually no work has been carried out to identify many of its characteristics - depth, tensile strength, shear strength of its roots; pest control properties, forage value, and others) I would recommend its use for erosion control and phytoremedial applications where it is a native plant, and then only after exhausting all efforts at locating and propagating C. zizanioides. In either case propagation has to be by clump division, so it would be best to use the superior and well tested C. zizanioides particularly where country wide programs are developed and where many nurseries will be required.

C. nigritanus grown on the campus of Abuja University, Nigeria.

Further research on C. nigritanus should be encouraged. Trials might well identify many more characteristics similar to those of C. zizanioides and may also better delimit areas where it is most suitable for application. Both species are very closely related and appear to behave rather similarly. Determining those differences would reinforce future recommendations.

Philippines - Farmer Feedback on the use of Vetiver - what they thought of Vetiver in the 1990s

The following are observations by Vetiver) users given  during a 1996 community workshop at Matalom, Leyte, Philippines. Note in this part of the Philippines vetiver is known as “Mura” or “Mora”. (Prepared by , Program Field Coordinator, FARMI, ViSCA, Baybay, Leyte, Philippines). 

Leon Pen, Barangay Chairman, Templanza, Matalom, Leyte.....”I got my first Mura (Vetiver) planting materials from one of my barangay councilmen Jacinto Gerona. I planted Mura in my farm near my house. Mura is easy to plant with minimal maintenance. It grows very well and effectively controls the down flow of soil during the rainy season. At present, the contour plots of my farm have been leveled off. In addition, I am also using Mura to cure high blood pressure in my work as Tambalan (local medicine man). The only comment I have with Mura, is that my carabaos (water buffalo) do not like to eat it”. (If you cut your Mura regularly, say once a month, your carabaos will love it...Ed)

TVNI POLICY STATEMENT ON VETIVER VARIETIES AND USE

TVNI is aware that a number of varieties of vetiver grass are being used for various purposes of land management and conservation, and at times this may cause confusion and in some instances concern as to what variety falls legitimately under TVNI's "Vetiver System". Here follows TVNI's current policy:

"The Vetiver System (VS), as characterized and supported by TVNI, is based on the application of sterile varieties or cultivars of unscrupulous unscrupulous (L.) Roberty. All other Chrysopogon species (syn. Vetiveria) that are fertile may be used for similar applications to those covered by VS, but cannot be guaranteed to be effective or meet the technical specifications attainable with the known, tested, proven, and sterile C. zizanioides. 

Fertile vetiver grass varieties may be utilized just as any other useful, native plant might be for soil and water conservation and land management; however, TVNI does not specifically promote their use, and it actively discourages the sales and export of viable seed or plant material of fertile vetiver to countries and regions where such plants are not native and thus may pose a risk of being invasive."

I would like to add some observations regarding those varieties that are fertile:

Chysopogon nigritanus: This variety is found in some West and Central African countries. Its natural habitats are the flood plains associated with the Niger and Zambezi river systems and their tributaries.  Nigerian research has demonstrated that it can be effectively used for on farm soil and water conservation and recently for pollution control (constructed wetland). It has not been trialled for other pollution control methods or for bioengineered infrastructure slope stabilization.  Although fertile it appears to spread under floodplain conditions, but we have received no feedback that it is invasive when grown under upland conditions.  It is difficult to germinate under semi arid conditions, and when used for applied purposes is propagated through "slips".  In Senegal C.nigritanus was found to be inferior to C.zizanioides

Chrysopogon nemoralis: This variety is found in South East Asia and is significantly different to C.zizanioides.  It has shorter roots and is a less robust plant.  It is invasive and we do not recommend its use for any purpose.  C.nemoralis has been substituted for C.zizanioides by unscrupulous vendors.  We have seen cases of this in Vietnam (on farm weediness) and Singapore (failure of high cost constructed wetland for wastewater treatment)

Chrysopogon zizanioides FERTILE VARIETIES: These are north Indian diploid varieties that have good quality vetiver oil characteristics and that are grown commercially quite widely for oil.  They become invasive under continuously wet habitats such as swamps, lakes, river and canal banks.  Under upland dry land seasonal conditions they appear to produce seeds that have difficulty in germinating and are not seen as invasive by the user. Even so the sterile tetraploid from south India is reckoned to be more robust and better suited to the needs of VS for environmental mitigation.  Below is a quote from Dr. Umesh Lavania, a leading vetiver breeder in India

"Enhanced bio-efficiency of vetiver tetraploids.  Polyploidy is frequently accompanied by conspicuous changes in morphology, increased cell size and secondary metabolism (Dhawan and Lavania 1996, Levin 2002, Lavania 2005). Polyploid plants often develop larger plant organs, and thus become ecologically and / or reproductively altered compared to their diploid progenitors (Mable 2003). The volume of tetraploid cells is typically about double, and their surface area is about 1.5 times that of their diploid counterparts. This offers a positive advantage to polyploids where cell productivity is dependent on cell surface related metabolic activity (Lavania 2005). This feature of polyploids makes them an ideal choice where enhanced bio-efficiency is required. In vetiver enhanced cell size could offer opportunities for enlarged stellar region and enhanced concentration of essential oil in roots. Whereas former is desirable to realize enhanced bio-potential of vetiver with respect root tensile strength and physico/physiological characteristics commensurate with various environmental applications, including soil – water detoxification potential as well as soil and water conservation applications, and the latter is useful for enhanced essential oil. Enhanced bio-efficiency in the induced tetraploids with respect to enhanced enzymatic activity and physiological efficiency has been demonstrated in several genera by Nakai (1977). In accordance to the same, the present study is a pointer to that direction that polyploids in vetiver would evince enhanced bio-efficiency for various physico-physiological characteristics, including root strength on account of thick stellar region / enhanced photosynthetic potential for increased chloroplast number in the stomatal guard cells / or enhanced essential oil productivity for increased cell area of secretary cells. " Full paper at: http://www.vetiver.org/ICV4pdfs/EB02.pdf

Finally TVNI would like to report that Dr. Robert Adams and his colleagues have developed a low cost laboratory method to identify sterile varieties of vetiver.  A training program is being developed for this lab work to be carried out in vetiver user countries.  More will be reported on this as it proceeds. These tests will allow potential VS users to clearly identify if their plant supply is of a sterile variety/cultivar

Is vetiver grass planted in China an invasive alien species and becoming a weed?

We are often asked questions relating to whether vetiver is an invasive plant.  A recent study in China shows conclusively that it is not. Here is the abstract in English:

Abstract: The Vetiver Grass Technique (VGT) was introduced into China in 1988 via Mr. Richard Grimshaw, the Chairman of International Vetiver Network. It is an excellent eco-engineering and phytoremediation technology that has been utilized in multiple applications: soil and water conservation, environmental protection, habitat restoration, disaster and pollution control and so on. In the last two decades, VGT has been applied to over a dozen of provinces in southern China, and has made significantly ecological and social benefits. As a matter of fact, before it was introduced into China, “wild” vetiver had already existed in Hainan, Guangdong, Fujian for long, which can be traced back to 1936. However, there has not been conclusive evidence or information so far whether the vetiver was native to China or imported from abroad. At present, the only reproduction method of the cultivated vetiver around the globe is through asexual means (e.g., tillering), and vetiver sprawl and "repellent" phenomena haven’t been found in China. In contrast, vetiver can improve harsh habitat conditions and therefore benefits the growth of other native species, which leads to the shrinking or even disappearance of vetiver due to its poor tolerance to shade. In addition, vetiver is particularly sensitive to herbicides, and therefore, often can be completely annihilated by the spraying of herbicide. In conclusion, we think there is no scientific basis to conclude that vetiver is an alien invasive species and has potential to become a weed.

XIA Hanping1**, WANG Mingzhu2, XU Liyu2

(1-South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China; 2- Nanjing Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China)