Zoom: Growing Science

Bob Mangan
Fun fact: This hanging Spanish moss, which is not a moss at all, belongs to the same family as pineapples. In this section of the greenhouse, Bob Mangan also takes care of a tree with roots that grow upward to gain moisture from clouds and ferns whose leaves are dotted with spores that spawn new plants (both not pictured).

For more than 45 years, Bob Mangan (’77) has built a living library of rare plants—and the stories behind them.

Story and photographs by Bryana Quintana

April 20, 2026

Vanilla orchid vines
When these chocolate trees flower, Mangan pollinates each blossom by hand with a paintbrush. SDSU emeritus professor Jim Alexander saved these trees, now woven with vanilla orchid vines, from a fungus that ravaged the chocolate industry decades ago.

Editor's note: We are saddened to share that Bob Mangan passed away in April, shortly after this story was published. Mangan's memory lives on in the hundreds of plants he cultivated, the many faculty, students and staff he worked with on campus, and the great impact he made on the department of biology and university as a whole. 

Bob Mangan (’77) has dutifully tended to San Diego State University’s greenhouse over the past 45 years, and for nearly every one of its 400-plus plant species, he has a story.

In previous chapters of his life, the SDSU botany alumnus worked as an illustrator, bartender, bouncer—or, as he puts it, a “tranquility expert”—and nursery manager. But his true calling has always been botany. He has devoted himself to acquiring, growing and caring for each plant in what he describes as a “dying science.” During countless greenhouse tours, he has shared that devotion with visitors, students and anyone else with an interest.

Elephant’s foot plant
“Look at this guy: He’s got a little happy face,” Mangan says. The plump body of elephant’s foot stores water, and under drought conditions, the leaves drop, returning once moisture is replenished.

The greenhouse, run by the College of Sciences, dates back to the 1960s. Since becoming manager in 1978, Mangan has more than quadrupled its specimen count, including some that are rare and endangered. The plants support biology teaching, giving students a close-up view of processes such as how root systems work. They also serve as a research resource for labs studying plant growth and genetics.

Though Mangan retired in December, he still returns weekly as a volunteer. Here’s a sampling of what visitors may experience if they’re lucky enough to tour with Mangan.

Bromeliad plant
"I love bromeliads because they have real cute flowers,” Mangan says. Nearby is a staghorn fern (not pictured) he grew from a cutting he received at age 21 that peaked at about 400 pounds.
Pitcher plant
“Normally, sugar is a reward for doing something cool for the plant,” Mangan says. “With these, it’s a deadly lure.” The pitcher plant baits bugs with sweet nectar before the insects fall into digestive enzyme fluid.
Crested blue myrtle cactus
Neighboring this crested blue myrtle cactus are plants grown by biology faculty for researching genetic changes and testing different growing conditions. Not pictured, a dudleya species discovered by SDSU alumus Mark Dodero (’83, ’84, ’96).