Sand or coast rose-gentian

Sabatia carnosa Small

Herbs annual. Stems generally single, 4-angled with wings to 0.3 mm wide, 0.3–2(–3.2) dm, branching alternate or prox­imally occasionally oppo­site. Leaves all cauline at flowering time; blade elliptic to ovate or proximal occasionally obovate, 0.6–2(–2.7) cm × 2–9(–13) mm. Inflorescences open cymes; pedicels 2–40(–70) mm. Flowers 5-merous; calyx tube campanulate, 3.5–8.5 mm, commissural veins more prominent than midveins, ridged, lobes oblong-lanceolate to narrowly ovate-triangular, 3–20 mm; corolla white to pink, eye white to pale yellow, projections of eye into corolla lobes oblong, without a contrasting border, tube 2–5 mm, lobes spatulate-obovate, 4–10(–13) × 2–8(–11) mm, apex obtuse to subacute; anthers remaining straight or slightly coiling circinately. 2n = 28.

Flowering summer. Beaches, interdunal depressions, salt flats; 0 m; La., Tex.; Mexico (Tamaulipas).

Plants of Sabatia arenicola are densely leafy through­out. The vegetative parts are more succulent than those of the other species of Sabatia and darken upon drying (a useful character in identifying herbarium specimens). The mid-stem leaves of S. arenicola are mostly elliptic, widest near the middle, whereas those of S. campestris and S. formosa, to which it is most closely related, are mostly lanceolate to ovate, widest near the base.

Although Sabatia arenicola appears to be largely autogamous, it is now quite well isolated temporally from S. formosa. Molecular evidence indicates intro­gression of genetic material from S. formosa into part of the range of this species (N. B. Bell and L. J. Lester 1978).