4. Malaxis soulei L. O. Williams, Ann. Missouri Bot. Gard. 21: 343. 1934.
Microstylis montana Rothrock, Rep. U.S. Geogr. Surv., Wheeler, 264. 1879; Achroanthes montana (Rothrock) Greene; Malaxis montana (Rothrock) Kuntze 1891, not Blume 1826
Plants 11–60 cm. Pseudobulbs 5–15 mm diam. Leaves 1, at middle or proximal 1/3 of stem, sheathing leaf bases persistent, shredding; blade ovate-elliptic or oblanceolate, keeled abaxially, 2.4–15 × 1–5.2(–6) cm, apex acute. Inflorescences spicate racemes, rachis thick, slightly ridged or fluted, 6–22 cm; floral bracts triangular to lanceolate, 0.5–1 mm; pedicels 1.3–1.7 mm. Flowers 40–160, not resupinate, green to yellowish green; dorsal sepal ovate to elliptic, 1.5–2.8 × 0.8–1.3 mm, apex acuminate; lateral sepals ovate to elliptic, falcate, 1.5–2.8 × 0.8–1.3 mm, apex acuminate; petals strongly reflexed, filiform to linear, falcate, 1.3–2 × 0.2–0.3 mm, apex acuminate; lip suborbiculate-ovate to subquadrangular-ovate, 1.5–2.8 × 1.3–2.2(–2.5) mm, base hastate-auriculate, apex obliquely 3-dentate or retuse with apiculum in sinus; disc deeply concave, 5-veined; column 0.2–0.5 × 0.2–0.5 mm; pollinia yellow. Capsules ascending, ellipsoid, 7 × 3 mm.
Flowering Jul--Sep. Moist, wooded canyons and ravines, rocky open slopes, pine savannas; 2000--3000 m; Ariz., N.Mex., Tex.; Mexico; Central America.
Malaxis soulei grows in the Santa Catalina, Santa Rita, and Chiricahua mountains in Arizona, and in the Davis Mountains in Texas.
The flowers of Malaxis soulei are retained on the axis until the capsules are fully developed, unlike M. corymbosa and some other species where the flowers fall quickly if not fertilized. The apparently sessile flowers are a very distinctive characteristic of this species. The central apiculum of the lip may be obsolete, and the apex thus retuse.
The name Malaxis macrostachya has been applied to M. soulei (C. A. Luer 1975). It is a nomen confusum, however, and it is not clearly applicable to this species (L. O. Williams 1965).