On April 28, 2014, Council member Mary Kay Sigaty, on behalf of Ken Ulman, unveiled an arboretum on the campus of Howard County government in Ellicott City. Due to County Executive Ken Ulman's generous support, permanent identifying signs were placed at more than 40 important trees at the site. Brochures are also available to guide the public around the property, and an interactive map developed as a joint effort between the Forestry Board President Tricia Valentine and Howard County's GIS Department can be accessed on mobile devices.

"We work hard to protect our natural spaces throughout Howard County," said Executive Ulman. "I think people would be surprised to learn that there is so much diversity and preservation, even in unexpected places. I truly hope visitors to the George Howard Building will take a moment to walk around and appreciate what we have. Especially our young people." 

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Interactive Map

The Forestry Board and Howard County's GIS Department have collaborated to create an interactive map of the arboretum. The map may be enjoyed on both computers and mobile devices.

View Interactive Map

The interactive map will help you locate and identify the wonderful trees planted around the arboretum. Identification signs have been placed at 41 of these trees. Click on each tree name to see an illustration and more information about the tree. We hope this exhibit piques your curiosity and encourages you to look at the trees carefully and inquisitively.



The arboretum at Governor's Hill was opened by former County Executive Jim Robey in 1999. Significant improvements were made to breathe new life into the exhibit in 2014 thanks to generous donations by Ken Ulman.

The government center hill is sometimes called "Governors' Hill." The office buildings on it are named for four Maryland Governors: Howard, Carroll, Ligon and Warfield, all residents of Howard County.

The Howard Building, opened in 1978, is named for George Howard, son of John Eager Howard, a Revolutionary War hero for whom the county is named. George filled in after a Governor of Maryland died, from July 1831 to January 1833 and was then elected for a year's term.

The Carroll Building, opened in 1967, is named for Governor John Lee Carroll, Governor of Maryland from 1876 to 1880. He lived in Doughregan Manor, still owned by the Carroll family. His campaign opponent from the Know-Nothing Party unsuccessfully attacked Governor Carroll's Roman Catholicism.

The Ligon Building, connected to the Carroll Building, is named for Thomas Watkins Ligon, Governor of Maryland from 1854 to 1858. Ligon barely won over his Know-Nothing Party opponent from Montgomery County. Governor Ligon married into Howard County's Dorsey family.

The Warfield Building opened in 1973 and is named for Maryland Governor Edwin Warfield of Howard County, who held office from 1904 to 1908. He was previously a state senator and owned the Ellicott City Times from 1882 to 1886.

From: A pictorial History of Howard County by Joetta M. Cramm.


Trees at Governor's Hill

Governor's Hill has a fine collection of both native and exotic trees and shrubs. The complete list is below.

Common NameScientific NameMap ID
Smoketree Cotinus coggygria 1
Flowering Dogwood Cornus florida 2
Baldcypress Taxodium distichum 3
Dawn Redwood Metasequoia glyptostroboides 4
Sweetbay Magnolia Magnolia virginiana 5
Lacebark Elm Ulmus parvifolia 6
Scholartree Sophora japonica 7
Red Maple Acer rubrum 8
Korean Dogwood Cornus kousa 9
Flowering Cherry Prunus serrulata 10
Weeping Cherry Prunus subhirtella 11
Goldenrain Tree Koelreuteria paniculata 12
American Holly Ilex opaca 13
Mugo Pine Pinus mugo 14
Crimson King Norway Maple Acer platanoides 15
Hedge Maple Acer campestre 16
Northern Red Oak Quercus rubra 17
River Birch Betula nigra 18
Green Ash Fraxinus pennsylvanica 19
Pin Oak Quercus palustris 20
Saucer Magnolia Magnolia Xsoulangiana 21
Sassafras Sassafras albidum 22
American Beech Fagus grandifolia 23
Princess Tree Paulownia tomentosa 24
Pignut Hickory Carya glabra 25
Sweet Cherry Prunus avium 26
Silver Maple Acer saccharinum 27
Kwanzan Cherry Prunus serrulata 'Kwanzan' 28
American Hornbeam Carpinus caroliniana 29
White Oak (Wye Oak seedling) Quercus alba 30
Eastern Redbud Cercis canadensis 31
Nellie Steven Holly Ilex 'Nellie Stevens' 32
Crabapple Malus sp. 33
Boxelder Acer negundo 34
Tree of Heaven Ailanthus altissima 35
Black Locust Robinia pseudoacacia 36
Zelkova Zelkova serrata 37
Serviceberry Amelanchier arborea 38
Western Arborvitae Thuja plicata 39
White Ash Fraxinus americana 40
Eastern White Pine Pinus strobus 41


A wide variety of trees have been planted in the Howard County Office Complex; many which are native to the county, and many which are considered exotic. While probably not native to Howard County, the Bald Cypress (Taxodium distichum) is certainly native to Maryland.

Because this tree loses its leaves and branchlets in winter it has earned the name "Bald" Cypress. The needles are soft and flat, crowded on flexible stems. In autumn the needles turn brown and the entire brachlet drops. Unlike the Dawn Redwood (growing right next to this tree) which has opposite leaves, these leaves grow alternately and spirally around the branch.

The cones are less than an inch in diameter and nearly round. Growing at the end of the twig, these cones are gray, becoming purple or brown later in the year. These cones grow on very short stalks unlike the Dawn Redwood whose cones have stems of 1-2 inches.

The Baldcypress grows naturally in swampy areas, on river banks, and on the border of marshes. In such wet areas it can grow characteristic "knees", woody projections from submerged roots. A long-lived tree, it can grow well over 100 feet.

The Baldcypress is the state tree of Louisiana, and is found growing naturally as far north as the Delmarva peninsula. Excavations in Baltimore City uncovered the ancient remains of a Baldcypress swamp. The heartwood is notably resistant to decay and has been used for construction, railroad ties, piers and durable fenceposts.


Governor's Hill Arboretum is located near Route 40 and Roger's Avenue in Ellicott City, MD. Public parking is availbale. See Google Maps for directions.