There are 6,000 plants growing in the Botanical Garden, belonging to 3,500 different species. Certain of the specimens are notable for their historical significance, others are of particular botanical importance — belonging to species that are under threat or extinct in the wild — and still others bear witness to a universal natural heritage and have a fundamental role in many fields including medicine, food, art, manufacturing, ornamentation and culture. Many plant species were first introduced to Italy or Europe by way of the Botanical Garden, truly a hub of exchange ever since its foundation, given the ties it had with the Venetian Republic and the endeavours of scholars who travelled and engaged in relations with the Old World and the New.

The Botanical Garden is a veritable atlas of plants found on Planet Earth. At its heart is the Hortus simplicium, a garden laid out during the Renaissance for the study and cultivation of medicinal herbs. The plant collections are divided up thematically, organized on the basis of selected characteristics with the aim primarily of catching the attention of visitors and encouraging them to take a closer look. With the opening of the Biodiversity Garden greenhouses in 2014, the scope of interest has widened to take in the relationship between Plants and Humans and Plants and the Environment, focusing on climate change and responsible use of resources.