IRIDACEAE

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SISYRINCHIUM : Sisyrinchium rosulatum re-examined Primary author: Bruce A.Sorrie

In preparing a species account of Sisyrinchium rosulatum Bicknell for the Vascular Plants of North Carolina website ( LeGrand et al. 2023), I felt uncomfortable assigning it a native status, even though it is considered to be native and endemic to the southern United States ( Cholewa & Henderson 2002).The vast majority of specimens at the SERNEC data portal (SERNEC, sernecportal.org) from North Carolina and also from South Carolina were collected from roadsides, lawns, and other open disturbed sites. Very few were collected from apparently natural habitats, such as longleaf pine ( Pinus palustris P. Miller ) savannas and slopes near streams. However, the fact that nearly all North and South Carolina records of S. rosulatum are from disturbed habitats does not automatically render it an alien; there are a number of plant species native and endemic to the Southeastern United States that occur primarily in roadsides and powerlines, e.g., Crocanthemum rosmarinifolium (Pursh) Janchen.

Additional searches through SERNEC in 2022 revealed that throughout its distribution in the United States, S. rosulatum occurs in roadsides and other disturbed sites. The Atlas of North American Plants ( Kartesz 2015) maps it primarily on the coastal plain from southeastern Virginia to southern Florida, west to central Arkansas, south-central Texas (Bastrop and Travis counties), and southeastern Texas (Jackson and Matagorda counties). There are records extending inland to western North Carolina, northwestern South Carolina, northern Georgia, northern Alabama, and northern Mississippi. Neither Kartesz (2015, Cholewa and Henderson (2002), nor Weakley & Southeastern Flora Team (2022a) suggest that it extends southward into Mexico or the West Indies.

From the original description by Bicknell (1899) to the present, authors of floras and floristic works have treated S. rosulatum as native and endemic to the United States. Bicknell (1899) stated that it was “Very distinct from any of our eastern species, having its affinity with certain South American forms and a Mexican and Central American species which is perhaps unnamed.”

The earliest collection date of S. rosulatum is 1852 [Sullivan’s Island, SC, Gibbes s.n. (NY)]. This relatively early date is suggestive of native status, but by no means proof, as there are many native species in the Southeast that were not discovered until later in the 19th and 20th centuries, and many alien species documented as early as the late 17th and 18th centuries. Examples of early discoveries that were originally thought to be native to the United States, but later determined to be native elsewhere include Commelina caroliniana Walter ( India) and Modiola caroliniana (L.) G. Don (South America). Modiola , and perhaps also Sisyrinchium rosulatum , may have arrived in the U.S. via early maritime trade from old South American ports such as Buenas Aires, Argentina and Salvador, Brazil, many decades prior to the first specimen collections.