Skip to content
1927 Map of the Arboretum

Spontaneous Flora Collection

Dawson Pond, spring, 1928
Leitneria Path, spring, 1903
North Meadow, summer, 1915
Bussey Brook, summer

Within the Herbarium of Cultivated Plants at the Arnold Arboretum, there is a collection representing a truly “natural” part of the landscape: the Spontaneous Flora. This collection of 2,235 herbarium specimens document plant species that have grown or are currently growing “spontaneously” – either native or naturalized without human intervention. Most of the specimens were collected by Ernest Jesse Palmer (1875 – 1962) during his tenure at the Arboretum in the early 20th century.

After years of persuasion, Palmer was hired by Charles Sprague Sargent as a “collector-botanist” in 1921. A passionate, self-taught plantsman, Palmer published a groundbreaking piece in the Journal of the Arnold Arboretum in 1930 titled The Spontaneous Flora of the Arnold Arboretum (pdf), in which he described in detail the landscape that exists in the Arboretum and the results of his years of collecting and observing its naturally occurring plants. This list of spontaneous plant species serves as an excellent baseline for comparison with the current composition of the herbaceous layer on the grounds today. Palmer’s work continued by a handful of Arboretum employees and visiting scholars into the twenty-first century.

Before the Arboretum became the property of Harvard University, it was owned by wealthy merchant and gentleman farmer Benjamin Bussey. The spacious meadows, hills, and brooks were part of a three-hundred-acre estate called Woodland Hill. Trees were cut to supply wood to the city and make space for growing hay and grazing animals. When Bussey died in 1842, he left a great deal of his fortune to Harvard University and much of his Woodland Hill estate eventually became the Arnold Arboretum. Bussey had a passion for plants that inspired him to provide for the future of agriculture and horticulture. Though remnants of natural woods and open spaces have been left to grow wild, the majority of the land at the Arboretum is used for the cultivation of temperate woody plants from around the world. Palmer was interested in how the property’s spontaneous flora reacted to the drastic changes involved in constructing a botanical collection, and advocated the importance of documenting this information.

Navigate the tabs above more information about the collectors who contributed to the Spontaneous Flora, some notable collectionsnew initiatives for the herbaceous layer aimed at enhancing plant and soil health in the understory, and further reading about the herbaceous layer and spontaneous vegetation.

Meet the Collectors

Ernest Jesse Palmer
Ida Hay
Dr. Leslie Mehrhoff
2017 Isabella Welles Hunnewell Interns

The work E. J. Palmer accomplished on the Spontaneous Flora Project continued with the contributions of a few other notable characters in the Arnold Arboretum’s history.

Peter Shaw Green was a staff member at the Arboretum in the 1960s. In 1962, he wrote an article published in Arnoldia titled Herbaceous Aliens in the Arnold Arboretum that revisited Palmer’s collections and discussed the more attractive herbaceous species present on the grounds. Peter also collected a small number of spontaneous plants and verified the identity of many specimens with corrected nomenclature.

Ida Hay worked for the Arboretum for more than 20 years, beginning in 1970. She began her tenure as a herbarium assistant, and eventually became the manager of the Herbarium of Cultivated Plants.   Ida collected 34 specimens for the Spontaneous Flora collection in the 1980s. She did extensive collecting on the grounds to document the Living Collections, which included interesting or unusual non-accessioned plants.

Dr. Leslie Mehrhoff revisited the Spontaneous Flora Project in 2008 to document the changes in spontaneous vegetation at the Arboretum since Palmer’s early collections. His interest in Palmer’s work began when he sought reference material for the Massachusetts Invasive Plant Advisory Group (MIPAG), and an Arboretum visit inspired him to update the list. Les collected over 200 herbarium specimens for the Arboretum’s Spontaneous Flora Collection and his enthusiasm for the mission of the institution was unbridled.

Between 2012 and 2014, Walter Kittredge, Curatorial Assistant at the Harvard University Herbaria, pored over 2,000 plus specimens in the Spontaneous Flora Collection. Walter single-handedly verified each plant’s identity and relabeled each specimen. Considerable thanks and gratitude to Walter for his contributions to advance the authenticity and relevance of the Collection.

The 2017 Isabella Welles Hunnewell Interns accomplished a collaborative project focusing on the herbaceous layer of the Arboretum. Inventories employing the circular plot method were conducted  within the Tilia (linden) and Fagus (beech) Collections. Herbarium vouchers were collected from all spontaneous vegetation within these areas.Plant collectors on the grounds should avoid collecting any species of conservation concern and any that are locally rare to ensure that these plants have a better chance of spreading once again across the grounds. The Arnold Arboretum allows visiting scholars to access the living collections, including the spontaneous flora, for research purposes. More information is available here.

Notable Collections

E.J. Palmer (1875 – 1962) was a prolific collector of herbaceous plants and his herbarium specimens comprise the bulk of the Spontaneous Flora Collections. Arguably his most significant specimens are those of conservation value. Palmer’s collections document four species currently endangered in Massachusetts and ten currently watch-listed.

Additionally, Palmer collected 6 species of orchids. Today, the only orchids found in the collection are Cypripedium acaule and Epipactis helleborine – the latter of which is considered an invasive species in Suffolk County. Cypripedium acaule, commonly known as the pink lady’s slipper, was last seen on the west side of Hemlock Hill. A more detailed survey is necessary to confirm the presence or absence of Palmer’s full list of Arboretum orchids.

E.J. Palmer’s notable herbarium specimens include:

  • 4 endangered Massachusetts natives:
    • Ageratina aromatica lesser snakeroot – [Specimen barcode 00339729] – fruiting specimen – collected 26 September 1928 – dry rocky ledges, southeast side of Hemlock Hill
    • Asclepias purpurascens – purple milkweed – [Specimen barcode 00241751] – flowering specimen – collected 18 July 1924 – dry wooded slopes, west side of Peters Hill (rare)
    • Houstonia longifolia – long-leaved bluet – [Specimen barcode 00359662] – flowering specimen – collected 26 June 1925 – gravelly hills, Oak woods, near Aesculus collection
    • Senna hebecarpa – northern wild senna – [Specimen barcode 00423518] – flowering specimen – collected 3 August 1923 – borders and open woods
  • 6 orchids:
    • Cypripedium acaule – pink lady’s-slipper – [Specimen barcode 00338591] – flowering specimen – collected 13 June 1939 – in partial shade, Central Woods
    • Corallorhiza maculata maculata – spotted coral-root – [Specimen barcode 00423782] – flowering specimen – collected 25 August 1925 – dry woods, southeast side of Peters Hill
    • Platanthera laceragreen fringed bog-orchid – [Specimen barcode 00423784] – flowering specimen – collected 15 July 1930 – moist grassy slope, foot of Peters Hill, Crataegus collection
    • P. psycodeslesser purple fringed bog-orchid – [Specimen barcode 00423786] – flowering specimen – collected August 1923 – moist margin of Bussey Brook, opposite Hemlock Hill (rare)
    • Spiranthes cernuanodding ladies’-tresses – [Specimen barcode 00423789] – flowering specimen – collected 2 September 1941 – open springy ground, south side of Peters Hill
    • S. lacera var. gracilis – slender ladies’-tresses – [Specimen barcode 00423795] – flowering specimen – collected 2 September 1928 – meadow along Bussey Brook, near Pinetum

Herbaceous Layer Committee members collecting plants at Myles Standish State Forest, Plymouth, MA.
In November of 2017, several members of the Arboretum’s Herbaceous Landscape Committee (HLC) collected seed from 15 herbaceous species flourishing in Myles Standish State Forest, Plymouth, MA. Hand-delivered to propagators at the Dana Greenhouses, each lot was directly sown or germinated to enhance Arboretum collections. It is hoped these charismatic species will establish themselves quickly and begin to self sow. Pictured (left to right): Terry Huang, Irina Kadis, and Brendan Keegan collecting Pityopsis falcata (sickle-leaved golden aster) and Ionactis linariifolia (flax-leaved stiff-aster).

New Initiatives

Herbaceous Layer Committee

Our institutional commitment to excellence and leadership in the care and presentation of the Living Collections includes a robust program to ensure a healthy and sustainable growing environment. In recent years, these efforts have included the creation of perennial meadows and “no-mow” areas throughout the landscape, as well as the formation of an advisory group to guide future decision-making. The Herbaceous Layer Committee’s primary goal is to manage the herbaceous layer on the Arboretum grounds with a holistic approach. This includes surveying the current conditions and species make-up of the herbaceous layer, creating a list of desired plants to add to the grounds, managing invasive plants, and continuing to employ strategies aimed at increasing biodiversity and soil health. Seeds collected from wild plants will be accessioned into Arboretum databases, planted in the landscape, and their growth documented.

The Committee is processed wild-collected seeds of 15 species collected in fall 2017 from the Myles Standish State Forest in Plymouth, MA.  The seeds were sown directly in the landscape in the spring, and germinated and grown into plugs at the Dana Greenhouses for fall planting.

Kent Field

In 2014, Arboretum staff and interns from Norfolk County Agricultural High School gathered in Kent Field (the grassy meadow below the Sequoiadendron Collection) to plant herbaceous plugs including common boneset (Eupatorium perfoliatum), great blue lobelia (Lobelia siphilitica), and whorled milkweed (Asclepias verticillata). These North American natives were selected to support wildlife, increase biological diversity, and offer a progression of bloom for pollinators and visitors alike.

The successes in Kent field have led to the establishment of “no-mow” areas in other parts of the Arboretum. These zones need less input from horticulture staff and decreased soil compaction should improve the health of woody plants whose roots occupy the same ground.

Herbarium Digitization Project

In summer 2017, information on E. J. Palmer’s Spontaneous Flora collection was added to the Arboretum’s plant records database. The digitization of this information enables staff members and the public to conveniently obtain information on these herbarium specimens through online searches.

For more information on the spontaneous vegetation in the Arboretum:

  • Green, P.S. 1962. Herbaceous Aliens in the Arboretum. Bulletin of Popular Information 22(7): 49-56. [pdf]
  • Hetman, J. 2008-2009. The Weeds and the Wilderness: An Interview with Les Mehrhoff on the Spontaneous Flora of the Arnold Arboretum. Silva, Fall/Winter 2008-2009: 2-3. [pdf]
  • Palmer, E.J. 1930. The spontaneous flora of the Arnold Arboretum. Journal of the Arnold Arboretum 11: 63-119. [pdf]
  • Palmer, E.J. 1935. Second supplement to the spontaneous flora of the Arnold Arboretum. Journal of the Arnold Arboretum 28: 410-418. [pdf]
  • Weaver, R. 1974. Wild Plants in the City. Arnoldia 34(4): 137-252. [pdf]