Isotria medeoloides (Pursh) Raf.
Family: Orchidaceae
Small whorled pogonia
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Herbs, singly or rarely in small clumps, short-rhizomatous, 4-25 cm. Stems pale grayish green, glaucous; scales 2-4, near soil line, white to light green. Leaves pale grayish green; blade elliptic-obovate, 17-85 × 8-40 mm, apex acuminate, glaucous when young. Flowers subsessile, without nectar and fragrance; sepals arching, green to light green, linear-oblanceolate, 12-25 × 2-3 mm; petals light green, oblanceolate, 12-18 × 2-4 mm; lip light yellowish green to pale greenish white, streaked with green, obovate, 11-16 × 4-5 mm, lateral lobes narrowly triangular, margins involute, middle lobe rounded, margins slightly revolute, undulate; callus yellowish green, longitudinal, becoming elongate, with fleshy, wartlike papillae toward apex; column 8-10 mm; ovary 10-15 mm; rostellar flap reduced. Capsules 12-28 × 2-10 mm; pedicel of mature capsule elongating to 5-17(-20, rarely) mm. 2n = 18. Flowering May--Jun; capsules mature fall. Acidic soils, in dry to mesic 2d-growth, deciduous or deciduous-coniferous forests; typically light to moderate leaf litter, open herb layer (occasionally in dense ferns), moderate to light shrub layer, relatively open canopy; frequently on flats or slope bases near canopy breaks; of conservation concern; 30--1000 m; Ont.; Conn., Del., Ga., Ill., Maine, Md., Mass., Mich., Mo., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Vt., Va. Isotria medeoloides should be sought in Alabama, Arkansas, Indiana, Kentucky, and West Virginia. Isotria medeoloides is self-pollinating (L. A. Mehrhoff 1983). Nonflowering plants commonly have a white, arrested floral bud (1-2 mm).

Perennial herb 4 - 25 cm tall Stem: single, erect, hollow, somewhat stout, pale grayish green with whitish coating (glaucous), hairless, and terminated by flowers just above whorl of leaves. In non-flowering plants, the stem often bears a white, 1 - 2 mm long, non-maturing floral bud. Leaves: five to six, whorled, stalkless, pale grayish green, glaucous, 1.7 - 8.5 cm long, 0.8 - 4 cm wide, non-toothed, hairless, fairly elliptic, widest at middle, and gradually tapered to long-pointed tips. Before the leaves are fully expanded they are strongly drooping, but at maturity they are held at right angles to the stem. Flowers: one or two, terminal, very short-stalked, non-fragrant, yellowish green, somewhat large (2.5 - 4 cm long), bilaterally symmetric with sepals pointed forward, fairly erect upper petals, and nearly white lip, but lacking a spur. The reproductive parts of stamens, stigma and style are fused into a 0.8 - 1 cm long round column above the 1 - 1.5 cm long inferior ovary. Sepals: three, arching forward, green to yellow-green, 1.2 - 2.5 cm long (barely longer than petals), 2 - 4 mm wide, linear to inversely lance-shaped. Petals: three, fairly erect, light green to yellowish green, upper two 1.2 - 1.8 cm long, 2 - 4 mm wide, elliptic with round tip, and positioned close together over modified lip petal. The nearly white lip petal is about 1.5 cm long, 4 - 5 mm wide, three-lobed with two narrowly triangular, erect side lobes curling inward around the column, while the wide, round central lobe flares outward to a wavy edge. Terminal lobe of lip white with pale green to yellow-green, fleshy, lengthwise ridge that becomes covered with wart-like bumps as it elongates toward tip. Fruit: one or two, erect, 1.2 - 3 cm long, 0.2 - 1 cm wide, narrowly cylindric capsules held atop a 0.5 - 2 cm long stalk, and maturing in fall. Root system: of fleshy, slender, hairy true roots arising from short rhizomes.

Similar species: Isotria medeoloides is similar to I. verticillata, but that species forms large colonies, is generally larger, it has a purplish stem, green to dark green leaves, never more than one flower, dark purple sepals that are much longer than the petals (3.5 - 6.7 cm), the capsule stalk is much longer (2 - 5.5. cm), and the flower is fragrant. Also similar is the Indian cucumber root, Medeola virginiana, but that species has a solid, wiry stem with a coating of woolly hairs.

Flowering: May to very early June

Habitat and ecology: Extremely rare, only known from Berrien County, MI where it occurred in a former orchard on the floor of a sandy, damp flatwoods in a thin layer of humus under red maple, oak, and black gum trees, and associated with royal fern. Generally the species prefers acid soils in dry to mesic second growth forests with a relatively open canopy, and a light to moderate layer of leaf litter.

Occurence in the Chicago region: native

Notes: Unlike the other species of Isotria, I. medeoloides is self-pollinating, which probably explains the lack of fragrance to the flowers. This species is very rare throughout its range in the eastern United States and is listed as Endangered by the U.S. Environmental Protection Agency.

Etymology: Isotria comes from the Greek words iso meaning equal, and tria meaning three in reference to the three equal length sepals of the flower. Medeoloides means like medeola, referring to the similarity of stem and leaf arrangement to Medeola virginiana.

Author: The Field Museum

Not colonial, the individuals few and scattered; herbage glaucous; stem 1.5-2.5 cm; lvs as in no. 1 [Isotria verticillata (Willd.) Raf.]; peduncle 1-1.5 cm, fls selfed, inodorous, light green or yellow-green or partly whitish, without guide-lines; sep 1.2-2.5 cm; pet 1.3-1.7 cm; lip 1-1.5 cm, less emarginate and ornate; 2n=18. Open stands of second-growth hardwoods or pine- hardwoods; irregularly at widely scattered stations from s. Me. to N.C., w. to s. Ont., Mich. and Mo. May, June. Our rarest orchid.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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