Southern twayblade

Bifolium australe (Lindley) Nieuwland; Diphryllum australe Kuntze; Neottia australis (Lindley) Szlachetko; Ophrys australis (Lindley) House

Plants 8–29 cm. Stems purplish green, succulent, glabrous. Leaves: blade dark green, ovate, ovate-oblong, or elliptic, 1.3–4 × 0.5–2.1 cm, base often subcordate, apex obtuse to apiculate. Inflorescences 5–25-flowered, lax, 45–110 mm; floral bracts suborbiculate-ovate, 2 × 1 mm, apex obtuse; peduncle and rachis slightly glandular-puberulent; bracts, pedicel, and ovary glabrous. Flowers reddish purple; pedicel filiform, 4–6 mm; dorsal sepal ovate-elliptic, concave, 1.5 × 1 mm, apex obtuse; lateral sepals ovate, falcate, 1.5 × 1 mm, apex obtuse; petals recurved, oblong, 1.5 × 0.5 mm, apex obtuse; lip linear, 6–12 × 1.5–2 mm, base extended into 2 rounded, linear lobes, projecting distally, partially surrounding column, distal half split into 2 linear-lanceolate lobes with minute tooth in sinus; column 0.5–1 × 0.5–1 mm. Capsules horizontal, ovoid, 8 × 5 mm, with relatively few large seeds.

Flowering Jan (Fla.)--Jul. Rich humus of low moist woods, marshes, sphagnum bogs, usually in association with rhizomes of cinnamon fern (Osmunda cinnamomea) and royal fern (O. regalis); 0--1000 m; N.B., N.S., Ont., Que.; Ala., Ark., Fla., Ga., La., Miss., N.J., N.Y., N.C., Okla., Pa., S.C., Tenn., Tex., Vt.

Perianth parts of Listera australis persist as capsules mature. This is such a small orchid that it can easily be overlooked; it may have a wider distribution than recorded here.