The Botany and National Herbarium Division is formerly known as the Bureau of Government Laboratories and later the Bureau of Science established in 1901 by Dr. Elmer Merrill. He gave form and substance to the Division’s first 20 years of existence with the primary function of conducting basic research on taxonomy, systematics, conservation, and economic use of Philippine plants. It collects, preserves, and maintains a botanical reference collection of Philippine floras which led to the establishment of the Bureau of Science Herbarium (later known as the Philippine National Herbarium). The herbarium is considered the largest collection in Southeast Asia housing more than a million specimens dating back to the 18th century and a science library that was unequaled in the Far East.

Dr. Merrill also conducted numerous botanical expeditions across the country resulting in many important publications, the most popular of which were the “Flora of Manila” and “An Enumeration of Philippine Flowering Plants”. When Dr. Merrill returned to the United States in 1924, distinguished Filipino botanist Dr. Eduardo Quisumbing took over the Herbarium and Botanical Library and became the first Director of the Philippine National Museum. 

It is however unfortunate that during World War II (1939-1945), the herbarium became nothing but a part of history when most of its precious collections turned to ashes, including the building itself. But through the initiative of Dr. Quisumbing, a 15-year campaign resulted in the restoration of specimens in the herbarium from returned collections of its duplicates in Europe and the United States. 

With its rebirth, the Philippine National Herbarium (PNH) became the heart of the Botany Division with the present collections as results of collecting activities in the country in the last century as well as of the exchange programs with other herbaria here and abroad. Researchers from the division curate, conserve, and conduct researches in taxonomy, systematics, applied science, ethnobotany, conservation biology, and bioinformatics. Collaborative research activities are also being conducted in the fields of pharmacology.