Platanthera obtusata

(Banks ex Pursh) Lindley

Gen. Sp. Orchid. Pl., 284. 1835. 1835

Basionyms: Orchis obtusata Banks ex Pursh Fl. Amer. Sept. 2: 588. 1814
Synonyms: Habenaria obtusata (Banks ex Pursh) Richardson Habenaria obtusata var. collectanea Fernald
Treatment appears in FNA Volume 26. Treatment on page 556. Mentioned on page 551, 553.

Plants 5.5–35 cm. Leaves 1(–2, rarely), spreading-ascending on base of stem; bracts 0(–1, rarely); blade linear-oblanceolate, elliptic, or broadly obovate, 3.5–15 × 0.8–5 cm. Spikes lax. Flowers resupinate, not showy, greenish white to yellowish green; corolla commonly whiter than calyx; lateral sepals reflexed; petals rhombic, lanceolate-falcate, margins entire; lip descending, linear, narrowly lance-rhombic, or linear-hastate, with median basal thickening, unlobed, 2.5–8(–10) × less than 1–2 mm, margins entire; spur slenderly conic, 3–8(–10) mm; rostellum lobes directed forward, wide-spreading, rounded-angular; pollinaria straight; pollinia remaining enclosed in anther sacs; viscidia orbiculate; ovary rather slender to stout, mostly 3–10 mm. 2n = 42, 63 (American, as Habenaria obtusata), 126 (Eurasian, as Habenaria obtusata).

Phenology: Flowering Jun–Aug.
Habitat: Mesic to wet coniferous forest, forested fens, sphagnum bogs, stream banks, tundra, moist roadsides
Elevation: 0–3500 m


V26 1130-distribution-map.jpg

Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., P.E.I., Que., Sask., Yukon, Alaska, Colo., Idaho, Maine, Mass., Mich., Minn., Mont., N.H., N.Y., Oreg., Utah, Vt., Wash., Wis., Wyo., Eurasia [Platanthera obtusata subsp. oligantha].


The rare Eurasian Platanthera obtusata subsp. oligantha (Turczaninow) Hultén differs from the North American subsp. obtusata in its smaller dimensions and rhombic-lanceolate lip. It is also said to be densely few-flowered, although some Siberian material is comparable to American plants. Supposedly intermediate plants are reported from Alaska, and much material from that area is reduced in stature and with smaller flowers than typical of American plants. In most cases, however, lips are relatively slender, and the plants seem merely to be stunted by their environment. One or two collections from the Alaskan Peninsula and Aleutians, however, seem entirely referable to subsp. oligantha with dense, few-flowered inflorescences of very small flowers with rhombic-lanceolate lips and shorter curved spurs. Eurasian plants are reported to be hexaploid or perhaps sometimes triploid, and if the apparent ploidy differences delimit the taxa, then it should be possible to unequivocally identify Alaskan plants.

Selected References


Lower Taxa


... more about "Platanthera obtusata"
Charles J. Sheviak +
(Banks ex Pursh) Lindley +
Orchis obtusata +
Alta. +, B.C. +, Man. +, N.B. +, Nfld. and Labr. +, N.W.T. +, N.S. +, Nunavut +, Ont. +, P.E.I. +, Que. +, Sask. +, Yukon +, Alaska +, Colo. +, Idaho +, Maine +, Mass. +, Mich. +, Minn. +, Mont. +, N.H. +, N.Y. +, Oreg. +, Utah +, Vt. +, Wash. +, Wis. +, Wyo. +  and Eurasia [Platanthera obtusata subsp. oligantha]. +
0–3500 m +
Mesic to wet coniferous forest, forested fens, sphagnum bogs, stream banks, tundra, moist roadsides +
Flowering Jun–Aug. +
Gen. Sp. Orchid. Pl., +
Illustrated +
Habenaria obtusata +  and Habenaria obtusata var. collectanea +
Platanthera obtusata +
Platanthera +
species +