Dear Fugare sir, Santosh sir,Vijay, Satyendra sir and friends Thanks for the responses. Before understanding why Orchids are accepting exotic hosts, we should understand the germination process of Orchid seeds. Orchid seeds lack endosperm which in normal seeds act as a source of food for the developing embryo. Hence orchid seeds need to be associated with the specific fungi (mycorrhiza) for nutrition during their germination. Later they need association of other set of fungi which are usually endophytic. Seed germination is a very peculiar and tough stage but once the orchid seedling is bigger they can usually grow in nutritive condition which can be created due to debris around the roots etc. At the same time to understand the growth of fungi, fungi needs specific hosts too to grow, some are very specific and some can grow on more than one host where as the third group generalist and can grow on many kind of hosts. Orchid seeds when dispersed need a kind of platform where they dont get washed or blown away. The fissures and cracks on the bark of host trees create such ideal place for an orchid seed to sit in stable position. Then they need a particular fungi with which they can form associations. If an orchid is native to India, then it obviously means that the fungi with which it will get associated is also found in India in and/or around the same locality. Both orchids and fungi are a bit adaptive to the new environment (fungi is more adaptive). So if you plant a native tree then it helps in regeneration of the existing fungi that can be found on the bark. But if you plant an exotic tree then its not an ideal habitat for the fungi, although the cracks in the bark would be a good place for orchid seeds to sit. So if an epiphytic orchid is able to GERMINATE on a non native tree then it means that the fungi was able to adapt itself to grow on the non native tree as well. This can happen if the fungi is a generalist and can grow everywhere or IT ADAPTED to the new bark. If a fungi and other microbes keep adapting to a new environment (created by exotics) then its likely that they will loose adaptability to the original native habitat on a long run. This is when it gets tricky. During current trend it is believed that all seed plants come in association with a fungi at one point of their life, in some manner and this association form a critical part of their life cycle. In some seed, the seed coat needs to be decomposed for the cotyledons to emerge out. If such fungi goes extinct then the such seeds will never germinate. At the same time fungi and other microbes help in decomposing the dead organisms too. Imagine if they loose their adaptability to decompose. We say the plastic takes 70 years to decompose. Can you imagine without these microbes you cant even decompose a small apple !! forget about the kitchen waste which we collect every day. So the bottom line is, dont add anything exotic to a natural environment, not even in the name of it being bio degradable. By adding them we are adding poison to our natural environment in small doses and one day it will accumulate so much that we will loose the natural environment. Best regards Pankaj
On Wed, Mar 13, 2013 at 11:31 PM, Vijayasankar <[email protected]>wrote: > Thanks Pankaj for the thought-provoking note. I fully agree that there > should be an effective management of invasive obnoxious species. > > I feel that quarantine measures must be more strengthened in order to curb > the entry of obnoxious weeds. Few years back we observed an emerging > population of *Acanthospermum australe* (a new weed to India), in > Bangalore, Karnataka. We presumed that this could have entered through > imported poultry feed. Import of such materials and other seeds should be > strictly quarantined. > > > Regards > > Vijayasankar Raman > National Center for Natural Products Research > University of Mississippi > > > On Tue, Mar 12, 2013 at 9:59 PM, Pankaj Kumar <[email protected]>wrote: > >> Dear all, >> >> Recently I came across a post of Dendrobium barbatulum growing on Acacia. >> So I felt like writing about it. >> >> There are many ways to look at it, but ultimately it is not a happy >> moment in anycase. >> >> Orchid seed germination is strictly dependent on fungal association, so >> growing on Acacia means it was able to find a fungi (mycorrhiza) that was >> able to grow on Acacia which is native to Australia. Question is, did the >> orchids adapt to a new environment or the fungi? >> Many times we walk in the forests and even if we are very much careful >> and we dont wish to disturb the natural environment, we do throw things >> like fruits and vegetables (left overs from our food) saying that it is >> biodegradable. But can you imagine, an apple doesnt grow in the western >> ghats, then how does the apple get decomposed there by a fungi or bacteria? >> Microorganisms are everywhere, they just need a host to propagate. An apple >> decomposing fungi or bacteria cant propagate if there is no apple and hence >> no apple tree in the area is a kind of a biocontrol for that fungi or >> bacteria etc. But its human who alters the environment every where. Even by >> throwing a bio degradable apple on the floor in a non apple area, we are >> kind of adding very minor doses of poison to the environment there and its >> not good for natural habitat. >> >> Ever thought, how a pig virus that was supposed to infect only pigs could >> infect human being causing swine flu? Its not the adaptation of human but >> the microorganisms. >> >> Just somethings to ponder about!! and we must not encourage exotics to >> take over natural vegetation in India. >> >> Few days back I was attending one seminar by a guy from China. He is one >> of the two persons who manages the online Forest Herbarium database. People >> from all over china just upload their pics selflessly (something similar to >> what we do on efloraofindia). They also keep tracks of the exotic or alien >> plants. Recently they came across an invasive climber of Mikania which was >> uploaded by one of the citizen scientists for id. It was the first report >> of this invasive species from a particular county or area. Hence it was >> reported to authorities and they went to the concerned area and destroyed >> all individuals of this invasive species. India must have a proper invasive >> species management system before Lantana reaches the top of himalayas. >> >> Best regards >> Pankaj >> >> >> >> >> -- >> *********************************************************** >> *Pankaj Kumar*, Ph.D. >> *IUCN-SSC Orchid Specialist Group Asia >> * >> >> *Office*: >> Conservation Officer >> Orchid Conservation Section >> Flora Conservation Department >> Kadoorie Farm and Botanic Garden (KFBG) Corporation >> Lam Kam Road, Tai Po, New Territories, Hong Kong. >> >> *Residence*: >> 151, 1st Floor, Tai Om Tsuen >> Tai Po, New Territories, Hong Kong. >> >> *email*: [email protected]; [email protected] >> *Phone*: +852 2483 7128 (office - 8:30am to 5:00pm); +852 9436 6251(mobile). >> *Fax*: +852 2483 7194 >> >> -- >> >> --- >> You received this message because you are subscribed to the Google Groups >> "efloraofindia" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> >> > > -- *********************************************************** *Pankaj Kumar*, Ph.D. *IUCN-SSC Orchid Specialist Group Asia * *Office*: Conservation Officer Orchid Conservation Section Flora Conservation Department Kadoorie Farm and Botanic Garden (KFBG) Corporation Lam Kam Road, Tai Po, New Territories, Hong Kong. *Residence*: 151, 1st Floor, Tai Om Tsuen Tai Po, New Territories, Hong Kong. *email*: [email protected]; [email protected] *Phone*: +852 2483 7128 (office - 8:30am to 5:00pm); +852 9436 6251(mobile). *Fax*: +852 2483 7194 -- --- You received this message because you are subscribed to the Google Groups "efloraofindia" group. 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