Alnus serrulata

Alnus serrulata is a widespread tree or shrub found on stream banks, lakeshores, ditches, along the edges of sloughs, fields, and bogs of eastern North America, from Quebec to Nova Scotia, Canada, south to Maine and Florida, west to Texas, and north to Missouri and Illinois in the United States. There are over 1,800 occurrences of this species, which are potentially threatened by development, succession, diseases, drought, flooding, predation, invasive species, and other threats in some places. Little is known about threats or trends, but with a large range extent, a high number of occurrences, abundant habitat, broad habitat preferences, and no obvious intrinsic vulnerabilities, Alnus serrulata is considered secure.

Alnus serrulata occurs in eastern North America from Quebec to Nova Scotia, Canada, south to Maine and Florida, west to Texas, and north to Missouri and Illinois in the United States (FNA 1997). Range extent was estimated to be 3.5 million square kilometers using herbarium specimens and photo-based observations documented between 1993 and 2024 (GBIF 2024, iNaturalist 2024, SEINet 2024).

By applying a 1 km separation distance to herbarium records and photo-based observations documented between 1993 and 2024, there are estimated to be over 1,800 occurrences rangewide (GBIF 2024, iNaturalist 2024, SEINet 2024). According to FNA (1997): "Alnus incana ssp. rugosa hybridizes with A. serrulata (= Alnus serrulata var. subelliptica Fernald). Extensive hybrid swarms occur where the ranges of these species overlap, including the area along the St. Lawrence River and the southern edge of the Great Lakes."

Threats to Alnus serrulata are not well documented but potentially include development, succession, diseases, drought, flooding, predation, invasive species, and other threats in some places, though there is insufficient data, including anecdotal accounts, to understand scope and severity of threats for this species.