Washington Grove is dominated by 100 to 200 year-old Red, White and Black Oaks. Other common trees are American Linden, several species of Hickory, White Ash, Eastern Yellow Poplar (Tuliptree), Sugar and Norway Maples, Cherry, Butternut and Sassafras. The most dominant native shrub is Mapleleaf Viburnum. The herbaceous layer is sparse or non-existent in many areas but large patches of Mayapple and Virginia Creeper exist throughout the Grove. Other herbaceous plants usually exist in small solitary clumps. In spite of the competition from invasive plants over 110 native plant species are found in the grove.

Three events in the 20th century significantly impacted the Grove’s ecology. In 1904 Chestnut Blight was introduced in the United States from Asian nursery stock. Over the next decades the blight killed an estimated four billion American Chestnut trees, including those that were an important component of the Grove. Today American Chestnut sprouts can be found in the Grove, but these small trees never reach maturity before succumbing to the blight. In response, in the 1930’s school children from adjacent City School #1 planted hundreds of Sugar Maples in the Grove to replace the lost chestnuts; the Sugar Maples now represent a significant proportion of its large trees. Third, Norway Maples, imported from Europe and a significant part of Rochester’s street tree inventory, became established in the Grove, competing with and suppressing the regeneration of native trees; the dense shade of the Norway Maple’s canopy provides a perfect environment for the inhibition of the native understory, and for the establishment of invasive shrubs and ground covers.

The Friends, in collaboration with their public partner, the City of Rochester and the help of the community, are attempting to implement the fourth major change in the Grove by eliminating invasive plants and reintroducing native species. Since 2011 City of Rochester foresters have removed large Norway Maples from all but the North slope and the eastern boundary. The Friends continue to remove regenerating Norway Maples. The natural seed banks have, however, been inadequate to restore the herb and shrub layers and the Friends are working to introduce plants that are absent, scarce or not successfully reproducing in a typical Oak-Hickory forest community.

The original plant community can never be replicated; the success of the Sugar Maple plantings of 80 years ago is an example of how the community has been irretrievably altered. Within the decades to come climate change will push the southern limit of boreal species northward as more southerly plants on the northern edge of their range become more dominant.

The Grove is the home to the full complement of urban wildlife, including wild turkey and enough occasional visits of White Tailed Deer for deer browse to be a concern. We see evidence of porcupines, and for a time the Grove was home to a fox. During spring and fall migration the Grove is a major feeding and nesting area for birds; 142 species of birds have been observed over one 18-year period. Sightings of Pileated Woodpeckers are common.