A conversation with our plant explorers

by Deborah Blackwell, Marketing & Communications Specialist
November 26, 2018

Tiffany preparing a herbarium voucher of Carya texana

A conversation with our plant explorers

View of Shores Lake - Ozark National Forest

View of Shores Lake in Ozark National Forest.

Plant collecting is part of the foundational history for the Arnold Arboretum of Harvard University. Founded in 1872 by Charles Sprague Sargent in collaboration with landscape designer Frederick Law Olmsted, expeditions around the world have resulted in a woody plant living collection containing more than 16,000 holdings. The Arboretum’s inventory includes representation from the Far East, Asia, Australia, Europe, and North America. But once the explorers obtain the targeted specimen and seed, how does it make its way from the far corners of the world to the Arnold Arboretum, and to science laboratories across Harvard University?

Tiffany Enzenbacher, manager of plant production, and Kea Woodruff, plant growth facilities manager, returned from an expedition to the Ozarks in October, resulting in successful collection of 28 species native to the western south. This was the final 2018 expedition of the decade-long Campaign for Living Collections.


You spent a long day in the field searching for a specific plant specimen on your procurement list that you secured in Zipock bags. What happens next?

Tiffany: When we go back to our hotel or motel in the evening, we review and add to our field notes from the day, containing specimen, leaf, fruit and bark characteristics, height and width, habitat, neighboring plants, GPS coordinates, elevation, etc.  We reorganize our herbarium vouchers, which are our pressed plant samples. For each specimen we collect from, we take a cutting that displays the typical foliage, bark, and fruit or flowers, and the voucher can be used for future reference. We also plan for the next day. We have a tentative itinerary ahead of time, but based on what we have already collected, we decide where we want to focus our efforts next.


Do you use the same procedure with things you have collected that are not on your taxa list?

Kea: Yes, and we love finding things we weren’t expecting. For example, we came across a pale purple-to-white berried Callicarpa americana (or beauty berry.) Beauty berry typically has clusters of vibrant purple berries, and we had never seen one that had this color berry before. So, we decided to take cuttings off the plant to ensure it would be genetically identical to the specimen we collected in nature.

Tiffany preparing a herbarium voucher of Carya texana

Tiffany preparing a herbarium voucher of Carya texana.


You work with local and national agencies ahead of your expedition for approval and permits to collect these plants, but when you find something unexpected can you keep it?

Kea: We do always ask ahead of time if we can opportunistically collect while we are there. These opportunistic collections may be species that the Arboretum doesn’t have from this area or perhaps is a new species entirely for us. Then when we’ve finished, we provide a full report of all collections to the organizations we obtained permits from. If there’s a conflict with a species we’ve collected, then we will work with the organization to resolve it. Usually it’s a non-issue, as we all have the same goal of making sure the resources in their area are protected.


How do you get the specimen you collected back to the Arboretum? Do they allow these items on an airplane?

Tiffany: We ship our seed, cuttings, and divisions back to the Arnold Arboretum’s Dana Greenhouses (DGH) via Federal Express. On this expedition we did it on three separate occasions. On the expedition to Wisconsin that I went on last year, we did have to carry seed on the airplane, and I was nervous going through TSA [Transportation Security Administration] that perhaps all the seed wouldn’t pass through inspection. One species, Menispermum canadense or moonseed, I labeled as “toxic” on its bag, so when it arrived to the DGH, the staff would know to wear gloves to protect themselves. I was anxious that the TSA agent would read the word “toxic” and confiscate the seed. Fortunately, the seed passed through inspection without any question, and I carried it on the plane.


Is it safe for the seed and specimen to be shipped in a Federal Express box? What happens when it arrives?

Tiffany: Yes, it’s safe. Material is typically shipped overnight to Sean Halloran, the Arnold Arboretum’s plant propagator. We provide him a list ahead of time of what he can expect, so he’s already researched seed treatments and cutting protocols in order to ensure Arboretum greenhouse staff have the highest propagation success rate. The greenhouse staff also try to get everything processed as soon as possible because we have such an influx of incoming seed. For example, right after the Ozark expedition, greenhouse staff were anticipating nearly 200 seed from the North America – China Plant Exploration Consortium (NACPEC), and Plant Collections Consortium (PCC) from Japan on the most recent international expeditions.


Is it typical of any expedition for things to be processed and shipped quickly?

Tiffany: No. For the NACPEC and PCC expeditions this year, or any international trips, the seed must go through the USDA [United States Department of Agriculture] and APHIS [Animal Plant and Health Inspection Service], where it’s inspected. If it passes inspection it then gets mailed back to the Arboretum. It can take up to two weeks to receive those shipments. There are also limitations on what can be shipped through the permit. I hold the small seed lot permit for the institution, which is a document allowing a small amount of permitted seed – it’s either no more than 50 seeds per packet or the packet must weigh less than 10 grams.


What would constitute something not passing inspection?

Kea: Insects, pathogens, or seed species not outlined in the permit restrictions. Inspections are done to prevent any unpermitted or harmful biotic organism from entering the United States. As an expedition participant you want the seed you are mailing to the U.S. to be as clean as possible. So, you want to remove as much organic material that can harbor insects or pathogens.

Kea collecting viburnum divisions

Kea collecting viburnum divisions.


Essentially the seed must be cleaned?

Kea: Yes. What we collected domestically did not, but the seed that comes from international expeditions does.


How do you clean seed on an expedition?

KeaIt depends on what kind of seed it is. If you’ve collected something like a conifer cone, you would have to break down the cone and take the seeds out. If you collected a berry – and I’m not sure how they do this in a hotel room – you can put the berries in a blender believe it or not, to puree the pulp off the berry to easily remove the seeds. You could also ferment berries in a plastic bag until you can easily remove the flesh. They use a colander to completely rinse the fruit, set the seeds to dry on a coffee filter, and package the seeds once they are dry. There is a range of protocols. You may just be pulling a capsule off, like for a Carya (hickory), because the seed is encased in a fleshy husk. Afterwards, the explorers are also sorting the seed into groups to package.


Does cleaning maintain the integrity of the seed since seeds are living things?

Tiffany: Typically, it does not damage the seed or endosperm within the seed, however, we’re not letting it get to the point of fungi growing on the fruit we collect. We are just trying to get fruit soft enough, so that we can easily handle it. We sometimes use rubber around the blades of the blender to help protect the seed. And if we are processing a small lot of seed, we would err on the side of caution and process it all by hand with a colander.


For a home botanist or plant enthusiast who is on vacation, walking, hiking, or biking, and they find something of interest to them, do you recommend they “collect” it for their own garden?

Kea: I would strongly discourage this for many reasons. One is you don’t really know the stability of the population in the world, so you would not want to harvest a species of conservation status. Another reason is to limit spreading around species that may be invasive or bringing pests to new areas.

Tiffany: The difference in home gardening and what we do here at the Arboretum is that if someone is germinating tomato seeds for their vegetable garden, they buy a pack of seeds that are already clean, have been tested, and the germination success is very high. When we are collecting seed from the wild, they may be ridden with insects or diseases and may not even be viable. We are working to get the highest germination percentage.


Is there anything you would particularly like readers to know about your work on collecting expeditions?

Tiffany: I’ve received many professional development training and advancement opportunities from the Arnold Arboretum and Harvard University, but this experience and last year in Wisconsin have been some of the most enriching in my career. Also, knowing that what we collect will be studied and enjoyed by both researchers and the public gives me a sense of satisfaction.

Kea: My experience has been that Harvard University is very committed to doing things in a responsible way. The Arnold Arboretum and our work in the field is an example of that. Everything we collect is to be grown here or in partner institutions that are committed to plant research and conservation. The Arboretum’s collections help expand research in many fields, as well as preserve these plants for future generations. Once they are here, they become a resource not just for Harvard, but for everybody.  





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