Opuntia mesacantha Rafinesque ssp. mesacantha . Longspine Eastern Prickly-pear. Phen: Apr-Jun; Jun-May. Hab: Granite outcrops, coastal dunes and scrub, longleaf pine sandhills, pine forests in sandy soils, Gulf Coast barrier Islands (AL, FL panhandle, MS), riverine sands. Dist: S. NJ south to sc. GA, c. AL, c. and n. MS, and se. TN; disjunct in FL Panhandle, s. AL, s. MS; disjunct in w. LA. Throughout the southern Piedmont, Atlantic and Gulf Coastal Plain, but absent from the FL peninsula forming a disjunction between the Gulf and Atlantic coasts, as in O. drummondii, with which this subspecies is often associated, at least along the coast and in certain Piedmont populations on granite. See McAvoy (2021) for details of DE occurrence.

Origin/Endemic status: Endemic

Other Comments: This is the most common species in the Atlantic and Gulf Coastal Plain and Atlantic Southern Piedmont. O. mesacantha is a low-spreading shrub with typically spiny cladodes with 1-2 spines per areole (although populations exist with individuals with up to 6 or more spines per areole, while other population may consist of nearly spineless plants), those spines generally, but not always, strongly retrorsely barbed. This species was mostly referred to as O. humifusa var. austrina or O. humifusa var. humifusa by Benson (1982). Vegetative propagules of this taxon have been found widely dispersed in coastal areas after hurricanes. This is a tetraploid taxon (2n=44).

Synonymy: = K4, Majure et al (2017); < Opuntia compressa (Salisb.) J.F.Macbr. – RAB; < Opuntia compressa (Salisb.) J.F.Macbr. var. compressa – G; < Opuntia humifusa (Raf.) Raf. – C, F, Fl5, K2, Pa, Tat, Tn, W, WH3; > Opuntia humifusa (Raf.) Raf. – Ward (2009e); < Opuntia humifusa (Raf.) Raf. var. humifusa – FNA4, K1, Va, Benson (1982), Doyle (1990); > Opuntia pollardii Britton & Rose – G, S, S13, Ward (2009e)

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Heliophily: 9