Elephant Thorns or Duri Gajah is fast becoming a major problem in landscape not only in Malaysia but also in many tropical countries. The plant originated from South America but was brought to other parts of the world as green manure and cover crops. It first entered Thailand in 1947 and made its way to Malaysia soon after that. Today it has spread as far as Indonesia and Australia causing serious problems to human and animals. They can be seen to sprout out of unlikely places such as local electricity substations (TNB's substations), around campus, along riverbanks and lakes and ponds.

Water Hyacinth or locally called Keladi Banting is a native of South America and probably has been introduced to Malaysia in the early 1900's. This aquatic plant has purple flowers.
Its ability to float on water made it popular plant to decorate fish aquarium, ponds and lakes. It can be used to absorbing heavy metals from polluted water. However, in tropical climate this plant is a scourge all over the world causing losses to agriculture, water supply and blocking river transportation. Its fast rate of growth forms a thick mat of floating roots impossible to penetrate.

This fast growing tree was a popular roadside tree planted in Malaysian Landscape during 70's and 80's together with two other Acacia species , They originated from Australia, New guinea and parts of Indonesia. Known locally as Yellow Acacia or Akasia Kuning, this tree was planted all over Asia in plantations for pulp and paper as well as soft timber. Yellow Acacia's popularity is probably due to its ability to grow easily on infertile urban soils as well as on soils that has been disturbed such as on ex-mining land. Today, this tree is no longer a popular roadside tree in Malaysia but nevertheless it is found to be growing wild and out of control in many open spaces in Malaysian cities.

Another popular Acacia species that has made its entry into our Malaysian landscape is the Acacia Mangium or locally called Broad-leaved Acacia(Akasia Daun Lebar). This tree with light green broad leaves and conical shaped was introduced as timber trees in plantations for the pulp and paper industry in Sabah in 1966. The tree is native to Queensland, Australia aswell as Papua New Guinea, Irian Jaya and in parts of Indonesia. Today, Broad leaved Acacia is still planted in parks but its use as stree trees has been discouraged becuase of brittle branches. The threat from this species is that it is found growing wild almost in any open space in cities, rural areas as well as on the friges of forest.

Lantana Camara (Lantana).

Another plant that has made a way into the hearts of Malaysian gardeners is the Lantana spps. Known locally by its unpleasant name of Bunga Tahi Ayam (Chicken Dung Flower), this shrub originally came from South America. Today, Lantana exists in hundreds of varieties and hybrids and adorned many home gardeners.
However, once escaped into the Wild, Lantana can grow as a tall shrub and formed a dense thicker up to 5 meters high in open ground. The shrub can also grow as a scrambling plant under the shade of taller trees. Once they found their way into the open ground they will quickly smother other plants.