Buchnera americana

This record represents the narrow treatment of Buchnera americana, excluding B. floridana as a distinct species, as recognized in FNA (2019, vol. 17) and Weakley (2025). In contrast, Kartesz (1994, 1999) included B. floridana in B. americana.

Bluehearts (Buchnera americana) occurs in eastern and central North America, from southern Ontario in southeastern Canada to southeastern Kansas, Florida and Texas in the United States. In the eastern United States, it is considered extirpated or historical from Delaware, Maryland, Michigan, New Jersey, New York, and Pennsylvania, but appears to be stable and not particularly rare elsewhere. It is estimated that there are more than 300 occurrences rangewide. In the United States it is apparently most abundant in Missouri, southeastern Kansas, and Arkansas. Habitat loss is the primary threat to existing populations of Buchnera americana. The lack of prairie or woodland fire has led to rapid successional change in many sites; open prairie areas have gradually developed into closed forests. Without ongoing management practices that retain open prairie and open woodland conditions, the decline of this plant is likely to continue.

Bluehearts (Buchnera americana) occurs in eastern and central North America, from southern Ontario in southeastern Canada to southeastern Kansas, Florida and Texas in the United States. In the eastern United States, it is considered extirpated or historical from Delaware, Maryland, Michigan, New Jersey, New York, and Pennsylvania (FNA 2019, Weakley and Southeastern Flora Team 2025). Range extent was estimated to be 1,670,000 square kilometers, using herbarium specimens, photo-based observations, and NatureServe Network occurrence data collected between 1994 and 2025 (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2024).

By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025, it is estimated that there are more than 300 occurrences rangewide. In the United States it is apparently most abundant in Missouri, southeastern Kansas, and Arkansas (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2024).

Habitat loss is the primary threat to existing populations of Buchnera americana. The lack of prairie fire has led to rapid successional change in many sites; open prairie areas have gradually developed into woodlands. Without ongoing management practices that retain open prairie conditions, the demise of many populations is likely to continue. Although the Indiana Heritage Program remarked that the decline in a population of B. americana may be attributed to the prescribed burning regime implemented a site (IN NHP 1989), similar programs elsewhere have recorded no negative affects (Ladd pers. comm.). It is believed by most that this natural disturbance regime may be necessary for the species. Habitat loss arising directly from human-induced destruction has also led to the decline of B. americana populations in historic times (Brownell 1985). Continued disturbance from recreational ATVs, road construction, mining, and other developmental and recreational activities threatens many extant sites, including most of the remaining populations in Ontario, Canada. Loss of potential pollinators through insecticide application or loss of vector breeding habitat is also a potential threat to B. americana, the presence of pollinators within a given habitat would potentially enhance the viability of the population through increased genetic variability.