Isotria

Rafinesque

Med. Repos., hexade 2, 5: 357. 1808

Common names: Whorled pogonia orchid
Etymology: Greek iso, equal, and tri, 3 probably referring to 3 sepals of equal size and shape
Treatment appears in FNA Volume 26. Treatment on page 511. Mentioned on page 496.

Herbs, perennial, terrestrial, winter dormant. Roots long, slender, hairy with mycorrhizae. Stems simple, hollow, fleshy, smooth, glaucous. Leaves (2–)5(–6), appearing whorled. Inflorescences terminal; bracts absent. Flowers 1–2, resupinate, erect, yellowish green to white, yellow, and purple, subsessile to pedicellate; sepals of same color, linear-oblanceolate to lanceolate, of equal size; petals oblanceolate, elliptic-obovate, or elliptic-lanceolate, enclosing column; lip apically 3-lobed, lateral lobes triangular, margins involute; callus forming fleshy medial crest; column white, apex denticulate; anther operculate; pollinia 2, hinged, soft, mealy; rostellum obscure; pollen in tetrads, granular; ovary green, slender. Fruits capsules, commonly persistent through following growing season, erect, ellipsoid-cylindric, dehiscent in fall. Seeds 1.2 × 0.2 mm. x = 9.

Distribution

e North America.

Discussion

Species 2 (2 in the flora).

Key

1 Sepals green to light green, less than 30 mm; lip light yellowish green to pale greenish white, streaked with green; pedicel of mature capsule 5–17(–20) mm; stem and leaves pale grayish green. Isotria medeoloides
1 Sepals purplish brown, greater than 30 mm; lip yellowish green to white, streaked with purple; pedicel of mature capsule 20–55 mm; stem purplish to brownish green; leaves green to dark green. Isotria verticillata
... more about "Isotria"
Loyal A. Mehrhoff +  and Michael A. Homoya +
Rafinesque +
Whorled pogonia orchid +
e North America. +
Greek iso, equal, and tri, 3 +  and probably referring to 3 sepals of equal size and shape +
Med. Repos., hexade +
ames1905a +, homoya1977a +  and mehrhoff1983b +
Isotria +
Orchidaceae (tribe Vanilleae) subtribe Pogoniinae +