Ottawa, part of the Plant Research Institute of Agriculture Canada (formerly Canada Department of Agriculture). Established in 1889, the arboretum is Canada's oldest. It occupies 40 hectares (99 acres) and includes about 10,000 kinds of plants. Its special collections of flowering crabs, lilacs, lilies, and hedge plants are as much for experimental work and study as for display to the public. The Dominion Arboretum has three greenhouses, the largest of which (2,760 square m 【30,000 square feet】) is used for research. It also has an herbarium containing some 695,000 preserved plant specimens for reference purposes.