Growing a Museum Specimen

Learn about the life of a plant at the Arnold Arboretum of Harvard University.

By The Arnold Arboretum of Harvard University

Arnold Arboretum Google Maps Fly-by (2019-08-20) by Jonathan DameryThe Arnold Arboretum of Harvard University

The Arnold Arboretum of Harvard University is a public garden and research laboratory in Boston, Massachusetts. The Arboretum’s plant collection includes sixteen thousand trees, shrubs, and vines. Each plant has a story. This is a story about how one of these plants arrived at the Arboretum.

Campaign for the Living Collections Video (2019-08-20) by Jonathan DameryThe Arnold Arboretum of Harvard University

In 2018, staff from the Arnold Arboretum embarked on four expeditions to collect plants in the wild. Collectors went to China, Japan, the northwestern states of Washington and Oregon, and the central states of Arkansas, Missouri, and Oklahoma. These expeditions were part of a 10-year collecting initiative called the Campaign for the Living Collections.

Kea Woodruff on Arkansas-Oklahoma Expedition (2018-10-04) by Tiffany EnzenbacherThe Arnold Arboretum of Harvard University

Two Arboretum collectors—Tiffany Enzenbacher and Kea Woodruff—spent nine days travelling in and near the Ozark Mountains of Arkansas. Enzenbacher is the manager of plant production at the Arboretum’s Dana Greenhouses, and Woodruff was then the plant growth facilities manager at the Arboretum’s Weld Hill Research Building.

Tiffany Enzenbacher on Arkansas-Oklahoma Expedition. (2018-10-07) by Kea WoodruffThe Arnold Arboretum of Harvard University

The Ozark Mountains region is known for harboring some of the most biodiverse oak-hickory forests in the country.

Video showing approximate collecting location of Alnus maritima in Oklahoma (2019-08-29) by Jonathan DameryThe Arnold Arboretum of Harvard University

The collectors logged more than sixteen hundred miles on the expedition. On the final leg of the trip, the collectors detoured into Oklahoma.

Illustration of Alnus maritima by Charles Faxon (1896) by Charles Edward FaxonThe Arnold Arboretum of Harvard University

In Oklahoma, Enzenbacher and Woodruff collected seed of the seaside alder (Alnus maritima ssp. oklahomensis), which is a rare member of the birch family (Betulaceae). The seed of this species is produced in cone-like structures that are known as catkins.

This hand-drawn illustration of the seaside alder was prepared by one of the first Arboretum employees, Charles Edward Faxon. The illustration was included in the ninth volume of Charles Sprague Sargent’s Silva of North America, published in 1896. Sargent was the first director of the Arnold Arboretum.

Range map of Alnus martima (1977) by Elbert Little (USFS)The Arnold Arboretum of Harvard University

The range of the seaside alder is quite unusual. Until recently, the species was known to occur in only two far-flung locations: a small pocket in Delaware and Maryland and another in Oklahoma. This map from Elbert Little Jr.’s Forest Trees of North America shows the known populations in 1977.

Updated range map of Alnus maritima (1977) by Modified from Elbert Little (USFS)The Arnold Arboretum of Harvard University

Researchers discovered a new population of seaside alder in northwestern Georgia in 1997. The three geographically isolated groups are now considered distinct subspecies. Given this rarity, the International Union for Conservation of Nature has classified the species as endangered.

Botanical gardens and arboreta play important roles in conserving endangered plants. When these species are grown and stewarded outside of their native habitat, the plants are safeguarded through a technique known as ex-situ conservation.

Before the trip, Enzenbacher and Woodruff had obtained permits to collect the endangered seaside alder at two locations. One site was located along the Blue River, outside the town of Tishomingo, Oklahoma.

Ethan Lovelace, Matt Gamble, and Kea Woodruff at the Blue River (2018-10-08) by Tiffany EnzenbacherThe Arnold Arboretum of Harvard University

At the Blue River, Enzenbacher and Woodruff were accompanied by Matt Gamble and Ethan Lovelace of the Oklahoma Department of Wildlife Conservation.

Alnus maritima along the Blue River in Oklahoma (2018-10-08) by Tiffany EnzenbacherThe Arnold Arboretum of Harvard University

The collectors found seaside alder bearing seeds. Although the seed-bearing catkins were still green, the seed inside was ripe.

The collectors found seaside alder bearing seeds. Although the seed-bearing catkins were still green, the seed inside was ripe.

Alnus maritima growing in water (2018-10-08) by Tiffany EnzenbacherThe Arnold Arboretum of Harvard University

Seaside alder tolerates exceptionally wet conditions. At the Blue River, some of the alders were partially submerged in flowing water.

Collection sheet for Alnus maritima (2018-10-08) by Arnold Arboretum of Harvard UniversityThe Arnold Arboretum of Harvard University

In addition to obtaining seed of the alder, the collectors also recorded detailed information about the plants and their native habitat. These hand-written notes would later be entered into the Arboretum’s plant-records database. These records are especially important for research and conservation purposes.

Herbarium specimen of Alnus maritima (2019-08-08) by Harvard University HerbariaThe Arnold Arboretum of Harvard University

The collectors also prepared an herbarium specimen of the seaside alder. This dried sample provides essential documentation of the parent plants and will be referenced by researchers for centuries to come.

The collectors also prepared an herbarium specimen of the seaside alder. This dried sample provides essential documentation of the parent plants and will be referenced by researchers for centuries to come.

Shipment of plant collections at the Dana Greenhouses (2018-10-04) by Sean HalloranThe Arnold Arboretum of Harvard University

Seeds of the seaside alder were shipped via FedEx back to the Arnold Arboretum’s Dana Greenhouses, which Enzenbacher manages.

Bags of wild-collected seeds at the Dana Greenhouses (2018-10-18) by Sean HalloranThe Arnold Arboretum of Harvard University

Oil-rich seeds like acorns are shipped in cloth bags, while smaller seeds, like those of the alder, are shipped in plastic.

Sean Halloran counting seeds of Alnus maritima (2019-03-20) by Jonathan DameryThe Arnold Arboretum of Harvard University

At the Dana Greenhouses, staff sorted and counted seeds from the expedition. Here propagator Sean Halloran sorts seeds of the seaside alder.

Seeds of Alnus maritima after sorting (2019-03-20) by Jonathan DameryThe Arnold Arboretum of Harvard University

At the Dana Greenhouses, staff sorted and counted seeds from the expedition. Here propagator Sean Halloran sorts seeds of the seaside alder.

Sean Halloran with seed trays of Alnus maritima (2019-03-20) by Jonathan DameryThe Arnold Arboretum of Harvard University

For germination to occur, the seeds of some plant species require refrigeration, which mimics a winter cold period. Others require treatments that soften or weaken the outside of the seed. Every plant is different, and Arboretum staff have documented their propagation experiments for almost 150 years.

Halloran referenced these extensive propagation records, which indicated the seaside alder would germinate easily. The seeds could be sown and placed directly into the greenhouse.

Video of Alnus maritima seedling growth (2019-08-21) by Jonathan DameryThe Arnold Arboretum of Harvard University

After two weeks in the greenhouse, seaside alder seeds began to germinate. This video shows seedling growth over five weeks.

Shade-covered seedling nursery at the Dana Greenhouses (2019-08-19) by Jonathan DameryThe Arnold Arboretum of Harvard University

The following spring, seedlings of seaside alder were moved from the greenhouse and transplanted into a shade-covered seedling nursery. Chris Copeland, the greenhouse horticultural technologist, works with other greenhouse staff and interns to care for the plants.

Saplings in an outdoor nursery (2019-08-19) by Jonathan DameryThe Arnold Arboretum of Harvard University

The seaside alders will later be transplanted into the primary outdoor nursery. After two to four years, Arboretum staff will determine which specimens of seaside alder are performing best in the nursery and which should be planted on the Arboretum grounds.

Seaside alders will eventually find permanent homes in the Arboretum landscape, possibly alongside other alders that are located near a wet meadow at the main entrance. As part of the Arboretum’s collections, these alders will be stewarded by horticultural and curatorial staff for years to come.

Visitors can enjoy the understated spring flowers and curious seed-producing catkins. And this rare and endangered species can be easily studied by researchers, who will write the next chapter in the story of this living museum specimen.

Credits: Story

All images are the property of the President and Fellows of Harvard College and Botanical Gardens Conservation International. All text was provided by Jonathan Damery, who also curated the exhibit.

Learn more at www.arboretum.harvard.edu

Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
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