Magnolia grandiflora

Magnolia grandiflora is tree in a variety of forests and endemic to the southeastern United States. It occurs primarily on the Coastal Plain from southeastern North Carolina south to central peninsular Florida and west to eastern Texas, though it has been expanding northward and inland by naturalization from widespread use as a cultivated plant. It has established as an exotic species in the mountains of North and South Carolina westward to Arkansas and Illinois and northward to Delaware. Since it is commonly cultivated, estimating the number of wild populations is challenging, though there are likely thousands. Threats include development, silvicultural activities, invasive species, and hybridization with M. virginiana and M. grandiflora cultivars. With a large range extent and number of occurrences, abundant habitat, broad habitat preferences, and no obvious intrinsic vulnerabilities, this species is considered secure.

Magnolia grandiflora is endemic to the southeastern United States and occurs primarily on the Coastal Plain from southeastern North Carolina south to central peninsular Florida and west to eastern Texas (Weakley and the Southeastern Flora Team 2024). This species has been expanding northward and inland by naturalization from widespread use as a cultivated plant, and it has established as an exotic species in the mountains of North and South Carolina spreading westward to Arkansas and Illinois and northward to Delaware, Maryland, and West Virginia (Weakley and the Southeastern Flora Team 2024). The probable pre-Columbian range extent, referencing the physiographic province map in Weakley and the Southeastern Flora Team (2024), was estimated to be approximately 1.5 million square kilometers using herbarium specimens and photo-based observations documented between 1993 and 2024 (GBIF 2024, iNaturalist 2024, SEINet 2024). Including the expanded range increases the range extent estimate to be approximately 2.4 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 specimens and photo-based observations documented between 1993 and 2024, it is estimated that there are over 3,500 occurrences in the likely native range (GBIF 2024, iNaturalist 2024, SEINet 2024). Including the expanded range, it is estimated that there are over 5,000 occurrences rangewide (GBIF 2024, iNaturalist 2024, SEINet 2024). However, this taxon is commonly cultivated, and iNatualist observations (>18,000) were not evaluated for evidence of cultivation (iNaturalist 2024).

Although threats are not widely documented, this species is potentially threatened by development, silvicultural activities, invasive species, and other threats in some places. This species reportedly hybridizes with Magnolia virginiana, and interbreeding with naturalized or cultivated plants may be altering regional genetic variation (FNA 1997). However, their overall impact is likely negligible given the species' broad range, large number of occurrences, and no obvious intrinsic vulnerabilities.