Gampaha Botanical Garden, also known as Henarathgoda Botanical Garden is situated in the suburb of Gampaha. It was established in 1876 by the British to conduct experiments on exotic economic plants such as Rubber, and explore plant wealth and development of the economy in the colony. The first imported rubber tree to Sri Lanka was first planted in this garden and it was the first seedlings of Brazilian rubber tree ever planted in Asia. The garden consists of a large variety of plants and many of them are from every corner of the tropical world it is expanding over 43 acres (0.17 km2) and situated next to the Attanagalu Oya and surrounded by paddy fields, a man-made green environment, and secondary forest as well laid out with lots of interesting sections, eye-catching landscaping and many shrubs, bushes, and trees.

The garden hosts an extensive collection of palms, orchids, and trees endemic to the country. The garden is also home to nearly 80 bird species including ten endemic species, 18 species of mammals including Sri Lankan flying squirrel(Petaurista Philippensis) and 12 species of butterflies and 10 species of dragonflies. It is divided into an orchid garden, which hosts a rare specimen of Queen of Orchids(Cattleya), forest path, palms garden, Japanese garden, Educational garden and a medicinal garden, which houses a collection of trees producing arrow poison from Africa and Malaya such as Antiaris toxicaria.

Reference – Wikipedia