4. Isotria Rafinesque, Med. Repos. hexade 2, 5: 357. 1808.
Whorled pogonia orchid [Greek iso, equal, and tri, 3; probably referring to 3 sepals of equal size and shape]
Loyal A. Mehrhoff & Michael A. Homoya
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.
Species 2 (2 in the flora): e North America.
SELECTED REFERENCES
Ames, O. 1905–1922. Orchidaceae: Illustrations and Studies of the Family Orchidaceae Issuing from the Ames Botanical Laboratory…. 7 vols. Boston and New York. Vol. 7. Homoya, M. A. 1977. The Distribution and Ecology of the Genus Isotria in Illinois. Master’s thesis. Southern Illinois University. Mehrhoff, L. A. 1983. Pollination in the genus Isotria (Orchidaceae). Amer. J. Bot. 70: 1444–1453.
