Beyond the mounting rooms are cases upon cases of plant specimens—including an “economic botany” collection cataloging how plants have been used by mankind throughout history.

One of the herbaria’s foremost archival treasures is a first edition copy of “On the Origin of Species,” presented to Gray by Darwin himself and annotated by both of the legendary scientists.

Personal touches like those margin notes make the archives valuable to historians of science, says Rebecca J. H. Woods, an MIT graduate student who recently transcribed a lengthy letter by Jane L. Gray, Asa’s wife.

“When it comes to people’s letters, you get a sense of who they are based on how they write,” says Woods.

In the case of Jane Gray’s letters, they paint a portrait of Gray as a sensitive man with a wonderful sense of humor, says Lisa A. DeCesare, the herbaria’s head of public services and archives.

“He had a talent for picking any flowers by the side of the road, and before you knew it, it would be a lovely bouquet,” DeCesare says, sharing details she gleaned from hours perusing Jane Gray’s correspondence. “You can know the dates and what people studied, but when you read the letters, you really get to know things they didn’t even know they were sharing.”

INCH BY INCH, ROW BY ROW

Long before the herbaria became home to millions of specimens and started loaning items to institutions worldwide, it was a simple garden in Gray’s backyard.

When Gray, originally a medical doctor, became professor of natural history at Harvard in 1842, he set to work soliciting plant specimens from all corners of the globe.

“He saw that the way to start a collection was to get other people to send you things,” Browne says. “He was very skilled at that—very charming. He saw himself as a centerpiece of a wide web.”

After making a few expeditions himself, Gray sent letters to reel in exotic specimens from regions like the South Pacific, Europe, and East Asia. These letters are stored in the Gray Archive at the herbaria—a collection of great interest to the Harvard branch of the Darwin Correspondence Project because it contains Gray’s myriad exchanges with Darwin.

Of particular import to Gray was a series of specimens sent from Asia: when he compared Japanese flora to seemingly unrelated species in North America, he recorded his astonishment at the plants’ striking similarities.

That discovery, Pfister says, “fits into the Darwin story because it makes it easier to argue that life is connected.”

Despite starting his collection nearly from scratch, Gray created a store of botanical knowledge that was one-of-a-kind in North America, according to Pfister.

“He made it terrific,” Browne says of Gray’s garden. “It was an experimental garden, a pleasure garden, a teaching garden, just on the other side of the Quad.”