A decade ago, when Dr. Diazgranados was head of Bogotá’s botanical garden, he took on the construction of a new herbarium and the largest greenhouse in the Americas, before a change in mayoral administrations swept out its leadership and he packed his bags for London. At the Royal Botanic Gardens, Kew, he built a Colombia program from scratch, taking advantage of a landmark peace agreement that expanded possibilities for biological expeditions, eco-tourism and the development of plant-based products. He published a world checklist of useful plants, a virtually boundless, searchable database of species that supply food, medicine, fiber and fuel, or help mitigate the effects of climate change.

“Science is there, of course, to investigate, to understand nature, but also to help us protect the planet and improve our quality of life,” he said on a recent tour of the New York Botanical Garden’s science facilities, which are clustered, away from main walkways, in the northernmost corner of its 250-acre campus. “What I need to do now is figure out how this institution can respond better to these challenges.”

Dr. Diazgranado’s offices are in the garden’s glass-walled plant research laboratory, nestled in an old-growth oak forest. Here, researchers draw on collections of resins, seeds and plants preserved in spirits or in silica powder, along with vast banks of DNA samples and plant chemicals. “There’s a big range of work going on in here,” he said. “From understanding fruit and seed evolution and adaptation of plants to marginal habitats, to the potential consequences of climate change, all the way to diversification in the neotropics.”

Steps away in the garden’s stately, vaultlike herbarium complex, glass doors swished open to reveal a staff delicately laboring to press, label and glue onto acid-free paper the fruits of botanical fieldwork; on this day, it was one scientist’s haul from Peru. Nearly eight million specimens are stored in the herbarium, among them the leaves of frailejones that Dr. Diazgranados collected as a young researcher; about 40,000 more arrive every year from scientists in the field or from other institutions. The bridge between the botanical garden as a public attraction and a research facility is its living collection, whose plants are routinely sampled to help answer questions in plant genetics, structure and evolution.