Botany expert and nature aficionado Patrick Sweeney is the Collections Manager of the Yale Herbarium, a collection of preserved plant specimens at the Peabody Museum. The herbarium is home to approximately 350,000 specimens from all over the world, ranging from mosses and fungi to vascular plants. Sweeney took WEEKEND on a tour of the herbarium last week to explain why vegetation, Darwin, and exotic fruit get him going.

Q. So, what got you into botany in the first place?

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A. As I kid, I lived in a rural area in the South and we had square miles of forest behind our house. I’d take off and spend time in the forest and notice the different plants. Eventually, as I got into undergraduate, and eventually graduate, school I kept pursuing that idea. I was more intrigued by plant taxonomy, plant systematics and evolutionary biology in general. Looking at all of this diversity and asking, why and how.

Q. Did you have plant collections as a kid?

A. I did have little leaf collections, believe it or not, as part of Cub Scouts or something like that.

Q. Do you still actively collect?

A. Yes, in support of research that takes place here at Yale. We took a trip in 2009 to Ecuador and we’ve collected plants all along the Andes. We hope to go to Malaysia and Vietnam this summer to collect, if permitting and all of that works out.

Q. What are the specimens used for?

A. Their primary use is academic research, ecology, evolution, that kind of thing. Ecologists, taxonomists and evolutionary biologists are interested [in the collection] but we also get weird requests. For example, we got an e-mail from a guy at the Getty last year who was studying different varnishes that were used in the past and was wondering what they were made out of. He knew we had this great collection of resins collected from trees in South East Asia back in the 80s, and he asked for tiny bits to analyze chemically and match to some of the varnishes they were getting off their paintings.

Q. Do the specimens have a shelf life? How old is your oldest specimen?

A. We like to say that they last indefinitely, but we don’t really know. There are herbaria that were created in Italy in the 1560s and are still around. The challenge is keeping bugs and moisture away. Our oldest specimen that I know of is a moss that was collected in Europe in 1808.

Q. Are there any unique specimens in the collection?

A. We have a moss that was collected by Darwin during the voyage of the Beagle and we have a collection with the earliest material known from Connecticut. It’s a herbarium in book form…made in New Haven by Horatio Fenn, a medical student, who collected about 700 plants. The collection has been restored, but the actual plants inside are the way he put them in. They are plants collected around New Haven, although, even at that time, they are not all native to Connecticut.

Q. What is the weirdest plant you’ve ever seen?

A. One of the weirdest plants I know about — I haven’t seen this one — would be Rafflesia, this parasitic flower that grows in Southeast Asia. It produces flowers, which are pollinated by flies, so they stink and they look like rotten meat.

Q. Do you have one in the herbarium?

A. We don’t have it in the herbarium unfortunately. I’m not sure how you’d make a specimen out of Rafflesia, because it’s kind of fleshy.

Q. Could you preserve it using alternative methods?

A. Yes, most of our stuff in the herbarium is dried, but you could make a pickled specimen of Rafflesia. You can put fruits, flowers and leaves in alcohol and preserve them that way. Some herbaria have fairly large collections of pickled material but people tend to go with the dry stuff as pickled material is much more high maintenance as alcohol evaporates, jars break, lids don’t seal right and it takes up more space. People studying Rafflesia might make pickled specimens, although they would need a big jar if they want the whole thing intact. You could dry this certainly as people dry cacti.

Q. How about fossilized plants?

A. The fossils are next door. The Peabody has a Paleobotany collection, which is a separate collection from the Herbarium.

Q. What is your funniest experience with a plant?

A. It’s not a single experience, but visiting virgin tropical forests or other virgin environments with — at least we think — the flora intact. You walk into these areas and there is all this diversity that hasn’t been fiddled that much by man. One thing that really got me into plants I think is diversity, looking around at all these types of things and wondering how all this diversity came about. One way to begin getting to that is to start to understand what this diversity is to begin with and to characterize it.

Q. Are there any poisonous plants in the collections, can they be dangerous to handle?

A. We have poison Ivy and relatives and you wouldn’t want to handle those. We have other things that if you were to pull them out, grind them up and ingest them, they would be poisonous. For example, there are all these interesting herbs that were part of medieval european lore and were used in “witches’ brews,” like henbane and belladonna. Not to mention the tropical plants that could have some poison in them.

Q. What’s the greatest challenge in plant collecting?

A. Transportation, getting to remote places can be challenging but in this day and age permitting, and talking to the right people can be a challenge.

Q. What’s your favorite type of plant?

A. I have to say it’s the plants that I study, because they are the ones I know best. I know more about them, their evolution, their morphology and their distribution. They are called the mangosteens — you might have heard of them. They are native to Southeast Asia and they are a tropical tree group. They are distributed pan-tropically, so they are in South America, Madagascar, Africa, Southeast Asia. That is my favorite plant group, but I’m biased here because it is the one that I study.

Q. Are mangosteens, the fruit, tasty?

A. Yes, they are very tasty.

Q. What do they taste like?

A. It’s described in different ways. It’s sort of a combination between sour and sweet. Some people call them the “Queen of Fruit” and say that it is the most delicious fruit that you’ll ever have, but no one can track down the source of that quote.