Stems slender, 5 in. long, not thickened. Leaves narrow, lanceolate-linear, acuminate or acute, 4 in. long, 4 1/2 lin. broad. Scapes a little shorter than the longest leaves, flattened, short, about 4-flowered. Flowers as large as those of P. laxiflora, Lindl., nodding, greenish-white, with rose-coloured labellum. Bracts lanceolate, acuminate or acute, 2 lin. long. Pedicels 5 lin. long, scaberulous. Dorsal sepal lanceolate, acute; lateral triangular, acute, glabrous. Petals spathulate, acute, a little shorter than the sepals. Lip entire, hastate, recurved, as long as the sepals, pubescent, with a linguiform, fleshy callus in the middle. Column stout, short. Chin gibbous.
A very variable, erect, epiphytic or rarely lithophytic plant, 10–50 cm. long. Stems clustered, terete, to 30 cm. long, 4–7 cm. wide, clothed below by up to 3 tubular sheaths, 2–5-leaved above. Leaves linear-ligulate to linear-lanceolate, suberect, acute or subacute, 10–23 cm. long, 0.7–2 cm. wide, articulated to a tubular sheathing base. Inflorescence often shorter than the leaves, racemose or shortly branched, 5–20 cm. long; peduncle terete, covered with papery sheaths, 2–70 cm. long; rhachis terete, short, glabrous; branches short, suberect, 1–5 cm. long; bracts more or less imbricate, ovate, acute or acuminate, 2–4(–8) cm. long. Flowers glabrous on outer surface, white, tinged yellow and purple, to greenish yellow. Dorsal sepal lanceolate, acute, 6.6–8.4 mm. long, 2.8–3.7 mm. wide; lateral sepals very obliquely triangular-ovate, acute, 7.6–11 mm. long, 5.7–8 mm. wide, mentum conical, 5.5–9.5 mm. high. Petals oblanceolate, subacute or obtuse, 5.5–6.7 mm. long, 1.5–1.8 mm. wide. Lip clawed, 3-lobed above the middle, 6–9 mm. long, 5–7.3 mm. wide, ± pubescent on claw and in apical half; side lobes erect, rounded sinus between mid-lobe and side lobes obvious; mid-lobe triangular-ovate, acute, reflexed; disc with a fleshy central ridge dilated towards the apex. Column short, terete, truncate, 1 mm. long.
Island of St. Thomas Peak of St. Thomas, about 7200 ft., Moller.
in Bol. Soc. Brot. 5: 199 (1887); Rolfe in F.T.A. 7: 111 (1897); Summerh. in K.B. 13: 75 (1958); Piers, Orch. E. Afr., ed. 2: 116 (1968).
in Bol. Soc. Brot. 5: 199 (1887). —Rolfe in F.T.A. 7: 111 (1897). —Summerhayes in Kew Bull. 13: 74 (1958); in F.W.T.A., ed. 2, 3: 221 (1968). —Piers, Orch. E. Africa, rev. ed.: 116 (1968). —Cribb in F.T.E.A., Orchidaceae: 355 (1984). —Geerinck in Fl. Afr. Centr., Orchidaceae pt. 2: 413 (1992). Type from São Tomé.
in Bol. Soc. Brot. 5: 199 (1888); F.T.A. 7: 111.
in Bolet. Soc. Brot. v. 199.