Plants on the go

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By 2017-09-10

By Risidra Mendis
Ceylon Today Features

Plants moving from one place to another may sound strange to some of us who are most often used to seeing them in gardens or at plant sales in many parts of the country. But plants just like humans and animals are a form of life and are known to migrate from one place to another. Even though plant migration is something new to most of us, the movement of plants from one place to another was recorded during ancient times. The migrating of plants in recent times however has like most other species also suffered the brunt of climate change.

Climate change is a much talked about subject these days. With temperatures rising in some parts of the world and dropping in other parts of the world it is not surprising then that plants are also struggling to survive in a fast changing climate that is conducive to some but not to others. With the change in the behaviour patterns of plants come other issues such as the healthy growth of plants and the destruction caused by the healthy growth of some other plants.

Commenting on how migrating plants are affected by climate change Research Professor, National Institute of Fundamental Studies and Former Director General, Peradeniya Botanical Gardens, Prof. Siril Wijesundera said plant migration has taken place from ancient times and that the movement of plants (migrating plants) from one place to another was recorded hundreds of years ago.

According to historical information about 200 million years ago, the continents were joined into one supercontinent. A supercontinent is a great landmass thought to have existed in the geological past and to have split into smaller landmasses, which drifted and formed the present continents. Each of several large land masses (notably Pangaea, Gondwana, and Laurasia) are thought to have divided to form the present continents in the geological past.

By 135 million years ago, Pangea had divided into two large subcontinents called Gondwanaland and Laurasia. In the great Southern subcontinent Gondwanaland, South America and Africa were connected with each other and with Antarctica, India, and Australia. This is roughly the time when the first flowering plants began to appear on earth. By 65 million years ago, about the time when dinosaurs became extinct, the continents had divided into positions resembling the present-day configuration.

"After the separation of the continents, fossil records show some of these plants in all the continents. Some of these migratory plants were found in Sri Lanka and other countries. After the continents got separated, the land between Sri Lanka and India also got separated. But despite the separation Sri Lanka and India still are on the same plate. Now you find different plants with different origins and Sri Lanka has endemic plants unique to Sri Lanka. Initially natural plant migration took place due to natural causes.
The Portuguese Empire at the time covered a good part of the earth and plants were brought by the Portuguese. There was a lot of plant movement during the Portuguese period. Food plants, crop plants, chillie plants, peanuts, and papaya plants were brought from South America and introduced to Asian countries and potato became the staple food in some countries. Rubber and tea plants were imported by the colonial people at the time. During the British period a lot of plant migration took place," Prof Wijesundera explained.
He added that some plants that were subjected to plant migration such as the water hyacinth (japan jabara) and salvinia became troublesome and damaged our natural biodiversity. "Some plants that were taken out of the country have become invasive in other countries. The Muslim Arabs also imported plants. Tamarind plants and coffee plants were brought by the Arabs.

The ocean, lakes and mountains served as barriers for plant migrations at the time. But people smuggled plants into countries through air travel. However tempted you are to bring in plants from other countries this is not a good practice because plants brought from other countries may have contaminants.

The coconut beetle that destroyed plants in Sri Lanka was brought into the country with orchid plants. Some plants can become invasive as they have many factors for uncontrollable growth. When an invasive plant is brought into the country the controlling factor is not brought with it and this results in the uncontrollable growth of the plant. Before forced migration took place, plants were confined to areas in their original habitats," Prof. Wijesundera explained.

He added that due to climate change some plant habitats became conducive nationally and internationally. "The drier plants occupied the dry climate. But when temperatures rise the growth of some plants increases. Climate change has also helped in the growth of some invasive species. A boost in growth of invasive species was seen due to climate change.

Plant migration can also take place by the help of animals. Birds can carry seeds on their bodies, feathers and paws. When the Indian Peace Keeping Force (IPKF) brought goats for human consumption these animals brought the plant Parthenium (Congress Weed) in their fur from India. Plant migration can be good and bad depending on the way it takes place," Prof. Wijesundera said.



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