Rhode Island’s List of Rare Plants Grows

By TODD McLEISH/ecoRI News contributor

The official list of Rhode Island’s rare and endangered plants has been updated for the first time in a decade, and the picture is somewhat grim. A total of 81 species were added to the Rhode Island Natural Heritage Database, bringing the total to 414, and 13 from the previous list were found to have disappeared from the state entirely.

Volunteer botanists, however, did find purple milkweed in West Warwick, R.I. (M.W. Fisher/Flickr)

Volunteer botanists, however, did find purple milkweed in West Warwick, R.I. (M.W. Fisher/Flickr)

Conversely, several species thought to have been extirpated were rediscovered, and a handful of others were found to be less rare than earlier surveys had indicated.

“Things are changing rapidly with the climate, and there is ongoing development pressure that affects plants,” said David Gregg, executive director of the Rhode Island Natural History Survey, which played a key role in updating the database. “New observations are being made all the time that change our opinion of the relative rarity of species.”

The Natural Heritage Database categorizes rare plants as either endangered, threatened or of special concern in the state, and a fourth category called “historic” indicates those species that once grew in the state but are no longer present.

Among the plants added to the database in the recent update are trumpet honeysuckle, a species common in the horticultural trade but which has declined in the wild; Canada dwarf-dogwood, also called bunch berry, which has struggled due to warming temperatures; and yellow blue-head lily, a northern species found more commonly on the mountain slopes of Vermont and New Hampshire.

Orchids are in especially dire straits in Rhode Island. Seven orchid species were added to the database, including yellow ladies’-tresses, large whorled pogonia, and north wind bog-orchid. Of the 36 species of orchids native to Rhode Island, 33 of them are now on the rare species list, and 10 of those are considered historic. The only orchids native to Rhode Island that are not on the list are the pink lady slipper and two kinds of rattlesnake plantain.

“Orchids are always rare on the landscape, but they’re also eaten by deer — they’re apparently really tasty — and they have very specific pollinator relationships and habitat specificity that make them at risk,” said Hope Leeson, a botanist for the Natural History Survey who participated in updating the database. “We’ve talked about adding the pink lady slipper, but it hasn’t made the list yet.”

Leeson said many of the changes to the database were the result of increased efforts by a large number of volunteer botanists such as Rick Enser, Doug McGrady and Francis Underwood spending time searching for particular species. A population of waxy-leaved meadow-rue was discovered by volunteers in Westerly, for instance, and purple milkweed was found in West Warwick and South Kingstown. Both species had been considered historic but have been moved to the endangered category.

Among the 10 species that volunteers were unable to find and, as a result, are now considered historic are lily-leaved wide-lipped orchid, dwarf burhead, three kinds of sedge, and budding pond weed, an aquatic plant that requires pristine water quality to survive.

Just three species were removed from the list because their population status in the state improved. Five others moved down the list from endangered to threatened or threatened to concern because they were found to be in less danger of extinction than previously believed. One of those, tall beaksedge, is considered a conservation success story because it benefitted from active monitoring efforts and habitat protection.

“We debated moving other species off the list entirely, but part of our reluctance was that even though we may have found more populations, they are still at risk from things that are going to continue happening in the future — climate change, habitat fragmentation, deer browse,” Leeson said. “Those are impacting rare species, and since rare species have such a specific habitat type that they have an affinity for, if you lose the habitat you lose the species.”

According to Gregg, the database is used in decisions by state and local environmental officials about land management and conservation, and by regulators and developers when properties are being considered for development. For instance, applications for permits to disturb wetlands must include a list of rare species found on the property.

Electric utilities often seeks information about rare species found on their transmission corridors as they make upgrades to power lines.

Many groups and individuals were involved in updating the list, including representatives from the Rhode Island Department of Environmental Management, U.S. Fish & Wildlife Service, Audubon Society of Rhode Island, Rhode Island Wild Plant Society and the New England Wildflower Society. The updated list was included in the state’s 2015 Wildlife Action Plan, which was reviewed by scientists and the public and approved by DEM in late 2016.

The database of rare animals in Rhode Island is being updated and should be completed by the end of the year.

Rhode Island resident and author Todd McLeish runs a wildlife blog.