Flowering
stems (20–)50–100 cm long, with dense, short, jointed, nonglandular hairs in
the inflorescence. Basal leaves (1–)4–6, present at flowering time, 5–26 cm
long, linear, glabrous. Flowers appearing as a single spiral along the
flowering stems. Sepals and lateral petals 6–9.5 mm long, white, the lateral
sepals free to the base or nearly so, only slightly spreading, oriented
parallel to the rest of the perianth or nearly so. Lip 6–9 mm long, ovate, the
margins irregularly toothed toward the tip, white, tinged with pale yellow in
the middle of the inner surface. Column 2 mm long, green. 2n=30.
June–September.
Widely
scattered in Missouri, mostly south of the Missouri River (eastern U.S. west to Texas; Mexico, Central America). Mesic and dry upland prairies, also in prairielike
embankments along roads and railroads, less commonly in prairie fens.
Spiranthes
vernalis is the tallest species of
ladies’ tresses in the state, and it flowers earlier than the other species
that have inflorescences appearing as a single spiral. As with many other
orchids, the number of flowering plants varies greatly from year to year, with
abundant flowering stems at some sites followed by years when the plants are
not noticeable.