Panicum amarulum A.S. Hitchcock & Chase. Section: Hiantes. Southern Seabeach Grass. Phen: Jul-Nov. Hab: Coastal dunes and shores, sand-flats, and longleaf pine sandhills. Dist: NJ s. to FL, west to se. and s. TX and ne. Mexico (TAM); Mexico (Yucatan: CAM, ROO, YUC); West Indies; restricted to the Coastal Plain except for WV (where apparently introduced). Primarily a coastal plant, P. amarulum has unfortunately been planted extensively in the Fall-line Sandhills of NC.

ID notes:Panicum amarulum and P. amarum are similar and sometimes confusable. They differ in general growth habit (long-rhizomatous with single stems in P. amarum vs. short-rhizomatous with dense multistem tufts in P. amarulum); foliage color (glaucous blue-green in P. amarum vs. green or yellowish green in P. amarulum); and panicle architecture (narrow, contracted, and spikelike in P. amarum vs. wider and more divergently many-branched in P. amarulum). Although the two sometimes co-occur in Coastal dune systems, P. amarulum is primarily a plant of secondary dunes and inland sands while P. amarum is most abundant on foredunes, upper beaches, and overwash flats (Virginia Botanical Associates 2023).

Origin/Endemic status: Native

Taxonomy Comments: Palmer (1975) reduced P. amarum and P. amarulum to infraspecific rank, but their broadly overlapping distributions and suite of characters suggests that they are separate lineages. Ultimately, this species is not part of Panicum sensu stricto.

Synonymy: = Bah, C, F, G, HC, RAB, S, SFla, Tat, Tx, WV; = Panicum amarum Elliott ssp. amarulum (Hitchc. & Chase) Freckmann & Lelong – FlGr, FNA25, NE, NY, Zuloaga & Aliscioni (2023); = Panicum amarum Elliott var. amarulum (Hitchc. & Chase) P.G.Palmer – K1, K3, K4, Meso6, Pa, Va, Lelong (1986); < Panicum amarum Elliott – Mex

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Wetland Indicator Status:

• Atlantic and Gulf Coastal Plain: FAC (taxonomic split from wetland indicator species)
• Eastern Mountains and Piedmont: FACU (taxonomic split from wetland indicator species)
• Great Plains: FACU (taxonomic split from wetland indicator species)
• Northcentral & Northeast: FACU (taxonomic split from wetland indicator species)

Heliophily: 8