Stream Orchid

Commonly found in marshy places, near springs and rivers.

Two very distinct color forms of this species have been published: Epipactis gigantea forma rubrifolia P. M. Brown, with deep red stems and leaves, and E. gigantea forma citrina P. M. Brown, with lemon-yellow flowers. Both are known from California.

The occurrence of this wide-ranging species in India and Tibet is based on Epipactis royaleana Lindley ex Royle being given as a synonym in a study of the Monocotyledoneae of Karakorum (W. B. Dickoré 1995) and an embryologic study (S. P. Vij et al. 1999).

Plants up to 90 cm, sometimes in large clusters. Stem glabrous. Leaves membraneous, flat, ovate to ovate-lanceolate, up to 15 cm long. Inflorescence loose, usually elongated up to 30 cm; rachis minutely pubescent. Lower bracts exceeding flowers. Flowers distant, spreading to pendent. Sepals green, veined with purple on outside, darker brownish-purple on the inside, ovate to ovate-lanceolate, up to 20 mm long. Petals slightly shorter, broadly ovate. Labellum up to 23 mm long, tinged with brownish-purple, with large hypochile and narrowly ovate epichile. Column including anther up to 9 mm long. Ovary sparsely pubescent, after flowering enlarged.

Plants to 1.4 m, essentially glabrous. Leaves 4–14, ovate, ovate-elliptic to narrowly lanceolate, 5–20 × 2–7 cm. Inflorescences lax racemes; floral bracts lanceolate to oblong, 7–127 mm. Flowers 2–32, rather showy; sepals greenish to rose-colored with rose-colored to purple veins; lateral sepals 16–24 × 8–9 mm, apex very oblique; petals pale pink to rose-colored to orange with red or purple veins, broadly ovate to ovate-lanceolate, 13–17 × 6–8 mm; lip marked with red or purple, strongly veined, distinctly 3-lobed, constricted at middle into 2 parts, proximal part papillose, calli red, minute, warty, lateral lobes prominent subtriangular wings, distal part linear-oblanceolate to narrowly spatulate-oblanceolate, grooved to tip, 14–20 mm, calli near base, erect, orange or yellow, winglike; column erect, short, stout, with pair of lateral processes, 5–10 × 3 mm; anther green; pollinia 2 pairs, yellow, soft. Capsules ellipsoid, glabrate or sparsely pubescent, 20–25 mm. 2n = 40.

Distribution: Himalaya Mts., eastwards to Nepal, Sikkim Bhutan; also in China and N. and Central America.

B.C.; Ariz., Calif., Colo., Idaho, Mont., Nev., N.Mex., Okla., Oreg., S.Dak., Tex., Utah, Wash., Wyo.; Mexico; Asia (China, India, s Japan, Tibet).

Fl. Per.: July.

Flowering throughout summer (Mar--Aug).

Wet gravelly and sandy stream shores and bars, may occur in riparian willow, box elder, and river birch woodlands or in chaparral, seepages, marshes, wet cliffs, hot springs; 0--3000m.

Amesia gigantea (Douglas ex Hooker) A. Nelson & J. F. Macbride; Helleborine gigantea (Douglas ex Hooker) Druce