REMEMBERING SOME PLANTS OF CHILDHOOD DAYS-PART III-Invasive Plants.

                           " A weed is a plant whose virtues have not been discovered "

                                                            -Ralph Waldo Emerson

       So far in the last two blogs I have mentioned about some plants from my childhood days memory

       which were useful plants. But, I can not forget to mention about few plants considered as useless,

       and obnoxious. Scientifically such plants are known as weeds.They often invade the locality and          dominate upon  other species  Such species become 'Invasive' for the locality. I remember that           a plant which appeared suddenly  in the area and grew rapidly was Kanak Dhutra, as locally
        named. A cutting of this plant was brought to the village considering it as an  ornamental but,
        it became invasive,obnoxious weed.In those days it was considered poisonous to both human
        animals. At present population of this plant is in decline. I would mention some of these of
        these invasive weed species in this blog.
   
        Kanak Dhutra-This is the first invasive plant species which comes to my memory of childhood.
         Suddenly this shrubby plant covered most of the non cultivable areas specially the road sides,
        around the margins of ponds and ditches.These ever green plants with beautiful white or pink
        flowers attracted all but,soon it became obnoxious and poisonous plants and we as child advised

to stay away from this plant. Efforts to eliminate this plant by cutting or uprooting proved unsuccessful .It was believed that the plant can grow in any surface.Scientific studies have revealed that 

like other weed species it has beneficial effects and can not be considered as obnoxious. This  plant originated from temperate North American region.Plants happen to be tall shrubs with cylindrical hollow stem. Broad leaves are heart shaped. These perennial plants 

produce clusters of flowers at the axils of leaves.Tubular,funnel 

shaped flowers are pink in colour.It has been found that consuming plant parts may cause paralytic effects in cattle.It has been found this plant can be used for making paper. The plant has medicinal 

values as sedative and anticonvulsant. Its chemical content has anticarcinogenic and cytotoxic

      properties. Scientific name-Ipomoea cornea sub sps.fistulosa, Family-Convolvulaceae.

    Putus-It is another invasive plant which persisted in large number   in different parts of the village.
    It is still persisting as, people consider it as less harmful plant..The thorny shrub produce dense tangle and cover the entire area over which the population grow.During those days a thick mass of .

 this plant was present around the Primary school.The pungent smell from these plant could be smelt from the class rooms specially, during rainy days.The plant happened to be a native of American tropics.it probably came to this area as an ornamental hedge plant.The fast rate of propagation and ability to survive under extreme condition helped to become an invasive plant. Plants happen to be perennial and can survive for more than two years.Angular stem being weak are climber like with visible glands in young condition at later stage become squarish covered with       spines  .Leaves are green and hairy with toothed margins . Flowers are produced in groups. These aromatic flowers are small tubular. These vary in colour ranging from yellow, orange red and white. This invasive and noxious species are mild poison for some herbivores. Fruits are small round berries which turn black when ripe. Attempts for control of this weed biologically remained unsuccessful. Some of the cultivars of Lantana are being widely cultivated as ornamental. This plant has number of uses. Dry stems of this plant are used as fuel used . Lantana leaves are  used in fever,flue,cold and cough. It has been found to provide relief in Rheumatism and joint pain.
Scientific Name of this plant is-Lantana camaca, family-Verbinaceae.

Water Hyacinth (Kochuripana)- This aquatic invasive plant was not present in the water reservoirs of our village but, appeared probably in the early sixties and occupied almost all water surfaces.

This South American plant was introduced in India as an ornamental plant.

but, it established very rapidly as an invasive aquatic weed. Rapid growth of  this plant with increase in biomass has helped to cover the water surface and interfering with the aquatic life present inside. Visible biological effect of this plant is drastic reduction in aquatic life underneath  due to change in the physio chemical characteristic and biological oxygen demand of water.
Considering its effect on aquatic lives it has been named as "Terror of Bengal". Growth of this plant has not only affected cultivation of fishes but also affected the water movement in irrigational canals by chocking and reducing water movement. Submerged delicate short stem of this plant bears fleshy green leaves .Green leaves have swollen base. These are borne in clusters. Beautiful showy flowers appear from the stem in groups. Generally these are violet or pink in colour. Long roots are produced from the stem. Although this plant has many harmful effects but, have a number of beneficial effects too. In Bengal dried plants are burnt and the ashes obtained are used as fertilizer. Its  phytotoxic property can be used for the control of some other weeds. Roots of this plant can absorb pollutants like Lead, Mercury and strontium thus, can be used in controlling water pollution. Scientific Name of this plant is-Eichhornia crassipes  
family-Pontederiaceae.

Parthenium Weed (Carrot Grass)-Parthenium or carrot grass is invasive weed which came to this area very recently. It has invaded the area probably through its seeds mixed with imported wheat.
Parthenium is a native plant of Mexico, Central America and Caribbean Islands. Rapid growth of this plant has helped it occupying places like road sides, waste lands and even agricultural lands. Phyto toxic chemicals produced by the plants have adversely affected   the associated plant species. Plants are annual herbs with branched green stem. Leaves are green having deeply divided margins. Fine hairs are present all over the plant.Numerous flower heads are produced in groups. Flowers are white in colour. Fruits or the achenes are small and hairy. Fruits are dispersed to distant places through parachute mechanism. Plants of Parthenium can cause skin disease on constant contact with human body. It may cause watery eyes, swelling of mouth and nose. Generally it is considered to be unpalatable to cattle but, recently I have noticed some affinity of goats towards this plant. Shortage of grazing fields due to growth of this weed has caused a serious problem. Although, this plant has no medicinal value. There is report regarding its use in fever,diarrhoea, neurological disorders, urinary track infection and in dysentery. Its scientific name
is-Parthenium hysterophorus  family-Asteraceae.

This blog mentions about only four plants which I found as invasive species. There may be more .One thing is clear that these species from different localities have ability to adapt new habitat quickly and to bully the native species to the point where they can not survive. Invasive species are often hardier, more demanding and ability to propagate at very fast rate. Being new to the habitat they have advantage of having no predators.Photographs plants included in the biog have been taken from web sources and are not author's own.
                 
       

  "  You can cut a tree down, and it grows back. Once a species goes, it's gone for ever."